There was a story few years back about burglars using Facebook status updates to find homes where owners were not home: http://bits.blogs.nytimes.com/2010/09/12/burglars-picked-hou...
So there is some evidence of using internet for this purpose. Those (supposedly) public Facebook updates are easier to find than TripIt calendars though.
The Dutch police force set-up two teams:
- One team of people with experience in scouting houses, who were sent on the road to find targets
- One team of IT experts wo were given the assignment to find targets via social media
The results were that spotting houses in the more 'traditional' way was about 8 times more effective than through social media. Therefore there's a much bigger chance they spot it with traditional methods, i.e. twig against front door.
So you have a much bigger chance of avoiding a break-ins by asking you neighbors to check your front door once a day (if you trust them..), than you do by not using leaky apps.
Also, at an airport it's much more effective for a burglar to spot tickets and baggage lables, than it is to sit down and hope that somebody connects to their access point and opens a valuable insecure connection.
The very fact that there's a story about it on nytimes.com is reason to think that it's uncommon. If it was common then it wouldn't be newsworthy.
Edit: what's with the downvotes? This is an easy and fairly reliable heuristic: if it shows up on the news, it's not worth worrying about, because newsworthy stuff is rare pretty much by definition.
