Anyone who attempts to pin the genesis of a huge media phenomenon down to a place, a day and a time, almost to the minute, can end up looking very silly indeed. But here goes. Widget frenzy began at 3pm (local time) on 24 May 2007, at the San Francisco Design Centre.
That, give or take a second or two, was when the founder and chief executive of Facebook, Mark Zuckerberg, ambled onstage and announced to an audience of around 750 web developers and technology bloggers - the latter tippety-tapping furiously on their laptops - that Facebook was to allow absolutely unrestricted access to widget developers. And Jiminy, while they were about it, they decided to push the boat right out - Facebook's software engineers would even be allowed to work with outside developers.
Few doubted that this would lead to a surge in activity. And hasn't it just - the numbers are mind-numbing. According to the monitoring company Adonomics, by mid-April 2008 there were 21,800 widgets in use across Facebook, and the total number of installs was in excess of 898 million. In any given 24-hour period, these widgets were being used a combined total of more than 34 million times. There were 200,000 developers with material either up and running or in development. By the time you read this, though, these numbers will be hopelessly out of date.
And, of course, given the magnitude of the phenomenon, it's almost unclassifiable. A web widget merely allows you to place an area of customised functionality (essentially a mini website) within another site. Facebook's most popular widget is Fun Wall, an uber-widget that makes it easier to share videos and games. This, however, is a phenomenon with a very long tail - how could it be otherwise when there are so many of the things out there? Many offer compelling functionality; others are largely decorative.
That's just on Facebook. Other social network platforms have had to follow suit in opening up. And this is not just about web widgets either: the Zuckerberg-inspired web widgets have also reignited interest in desktop widgets.
Tellingly, advertisers are interested in both types. Very interested indeed. Enthusiasm for web widgets was, in the earliest days, a result of nervousness about whether traditional online advertising formats were at all appropriate in the social networking space. Indeed, there have been a number of Facebook groups set up to oppose commercialisation of the site.
Widgets, the advertising community realised, offered opportunities to enter into a more comfortable relationship with the social networking community. Offer people useful and entertaining functionality for free and suddenly you're helping them, rather than shouting at them. The Adonomics numbers looked rather tasty, too.
There have been essentially two stratagems. First, to sponsor an activity totally unrelated to the brand. For instance, one of the most picked-over US examples is Honda's sponsorship of a widget offering access into exclusive music videos by the band Fall Out Boy.
The second approach, and seemingly the more fruitful one, is to offer a service directly related to your company's core activity, such as a recent initiative from the heath plan provider HSA - a personal planner widget that allows users to record appointments, as well as offering health tips and "Doctor, Doctor" jokes.
Clare Lee, the head of brand development at HSA, says the initial brief was to develop something new, clever and cost-effective in the online space: "Online is our most effective acquisition tool, but we've not been doing much in terms of branding. And this coincided with the introduction of a new brand identity - Mr Sleeve. So we got him a page on Facebook and launched a viral campaign to get people to make friends with him. That's when the online guys came up with the idea of the reminder service. It tied in really nicely."
Sceptics will point out that "cost effective" is arguably the most telling phrase here, and it's undoubtedly true that dipping your toe in this water remains a relatively cheap proposition. Despite the arrival of big guns such as Nike, Adidas and Coca-Cola, this year's UK widget development market will only be worth an estimated £5 million.
And producing the widget is only the start. Unless you're exceptionally lucky and it builds momentum on its own, you have to tell people about it, which means running a campaign either off- or online. But even here there are moves to make life easier. In April, Mediaforge launched a technology that will enable the conventional online advertising inventory - banner ads - to carry widgets. It's a two-birds-with-one-stone proposition: you download straight from the ad.
And Slide, the world's biggest widget-maker, made moves to underwrite the commercial future of the genre by signing a deal, again in April, with the commercial development company Monetise to help it forge closer links with UK advertisers and agencies.
The big question, however, is that perennially thorny one - do they work? Can widgets really help further the ambitions of brands?
Blake Chandlee, the commercial director at Facebook, admits that there's been little qualitative work, but points out that there's plenty of quantitative data. He adds: "Brands have to define their objectives, they have to respect customer environments, and they have to think about the metrics they intend to use to measure success, whether it be download numbers, engagement factors or impacts.
"It's a social environment, so the successful applications will be those that encourage sharing and collaboration. A good application is simply one that targets its audience well."
And Dan Calladine, the research director at the digital agency group Isobar, tends to agree. "It's too early in the commercial life of the widget to get too hung up about metrics. Research companies are starting to look at widgets and their effects on brand perceptions, but, at this stage, I don't think we should lose sight of the fact that they're a great way to get people interacting with your brand," he says.
Early it may be - but it's also true that the sector is moving rapidly beyond the cottage industry status it had last year. Back in November, the web pioneer Ivan Pope (the man who introduced cybercafes to the UK) organised a modest event in Brighton, called "widgety goodness", for a handful of like-minded souls. It created such interest that this year's event, which takes place in New York in June and in London in October, has the more grown-up title of "widget web expo".
Pope claims that widgets are just one manifestation of a fundamental shift in the way we produce and consume content online. Many leading ad agency thinkers agree.
Take Mark Fallows, the director of digital content at McCann Erickson. It's interesting that his most successful foray into this territory is a desktop widget for UPS that allows shippers to monitor the status of parcels within the system. It may feature the obligatory cartoon character, but, actually, it's a million miles away from the Facebook bumper-sticker world that initially fuelled this whole phenomenon.
And Fallows argues that, with the launch of new software such as Adobe AIR, we're about to enter a widgety world rich with even greater possibilities. "I think what we are witnessing is the natural progression of the web - where content and code becomes customisable, personalised and transferable," he says. "And from what I've seen of Adobe AIR, it will take desktop applications to another level altogether. It's going to be fun."