I'd bet you know of, and probably use, Wikipedia.
With nearly 625,000 entries, it is the largest free encyclopedia on the Web.
While most Wikipedia entries are written by readers and are peer-reviewed for accuracy, it isn't just regular work-a-day info hounds, or subject specialists that update Wikipedia.
From a look at some recent Wikipedia entries, it really appears that some smart p.r. people are taking advantage of Wikipedia's open posting policy to post product and company updates.
Take Skype, for example. Just a couple of days after Skype's latest release late last month, (220.127.116.11) the Wikipedia entry for Skype was updated to list that version.
More companies in the VoIP space ought to pick up the hint. New earnings report? Change your CEO? Key new alliance partner? New hardware? Software upgrade? Make sure you have your Wikipedia bases covered.