Back in September, Google announced the culling of a number of its lesser-used services. Among them was Sidewiki, the company’s attempt at Web annotation. Today users of the service have been sent an email informing them that it will close on 5 December.

Sidewiki was launched on 23 September 2009 as a browser plugin packaged with Google Toolbar. In Google’s own words, it allowed users to “contribute helpful information next to any webpage. Google Sidewiki appears as a browser sidebar, where you can read and write entries along the side of the page.” The video below, published on the service’s launch day, explains more.

As with many services from Google, Sidewiki’s arrival promped much hype and analysis online, but in the end users simply didn’t take to the idea of a universal comment system for the Web. In fact, Google-watcher Jeff Jarvis saw it as dangerous, as it effectively hid comments about a page from anyone who didn’t use Sidewiki, unlike comment threads embedded in a page itself. “Quite ungoogley, I’d say,” was his verdict.

However, Jarvis’ fears were for naught as Sidewiki never caught on. Google is now giving users until 5 December to export their data from the service (details here). After that date, all data will be deleted and Sidewiki will be no more.