Last night (9/13/12) my bikes were stolen from my alley. They broke the lattice above the door and climbed over.
You can't see the bikes from the street, so they knew they were there (my roommate was working on one bike in the street earlier that night so that might have been when it was observed).
I made a police report (before touching the back of the door, where they let themselves out). The officer that responded (who incidentally was the one that chased down and arrested one of the home invaders) said the surfaces weren't smooth enough to lift prints from.
It was a small black trek road bike and a medium/large schwinn road bike, nothing spectacular. If anyone sees any abandoned bikes or bike locks in the neighborhood, I'd be interested to know that. I've seen crappy abandoned bikes in alleys in the past and I suspect these people ride around on their bikes and ditch them while they ride the stolen ones away and come back and retrieve their original ones.
If you leave your bikes in your back yards/alleys, I'd recommend locking them in place.
If you discover a burglary remember not to touch anything.
If there is something suspicious call the police.
If the police catch the person, MAKE A STATEMENT!