Yep. I do it all the time. So do a lot of regular commuters who park in our racks. Remember to lock the ends of your cable and chain, though!

Some of you might recall my saga of my hijacked OnGuard mastiff chain. I neglected to secure the U lock one evening when I left, and the next day someone had used my chain with their own crappy Master lock securing it. I resolved the issue by locking my U lock to my chain, and leaving a polite note to call me when the owner wanted the bike released. It was a clueless first year medical student.

I've been keeping an eye on that "clueless" 1st year medical student's bike, and I realize the guy acually does just pack a Master lock with him and use whatever loose cable is available to lock up. More than one person leaves an end of their cable unsecured when they leave.