According to this CBC News story, if you post your vacation plans online, you might get robbed:
It’s now routine for police officers to ask robbery victims what information they put on Facebook and Twitter before the crime and if their online connections are true friends or potential suspects, according to [Cpl. Janis] Jean [of the Saanich Police Department, north of Victoria].
But as Andy Baio pointed out back in February, back in 1983, the Montreal Gazette warned against outgoing answering machine messages that tell callers you’re not at home. And in 1977, another article suggested that you shouldn’t list family weddings or funerals in the newspaper, lest you tip off would-be robbers.