This is topical - the CEO of Plazes was supposed to be speaking at Next Web in Amsterdam, but cancelled citing family problems. Then his own product showed him actually attending Reboot in Copenhagen, and the Next Web people got a bit upset. Eventually it turns out that it’s down to misunderstandings on both parties’ accounts, and some snarky blog posts get redacted.
The details aren’t really that important, but it’s a great illustration about how presence tools can lead to these kind of snafus. And it’s only going to get more common as we start to see tools that update your presence data automatically rather than manually - it’s only a matter of time before someone writes an app that takes GPS or cell location data from a mobile and streams it to something Twitter-esque. How long before the first cheating spouse gets caught out when they forget to switch that off?