Personally, I wouldn't be sitting around working in a Starbucks. Then again, I'm also the semi-paranoid type who won't use public wireless networks for work at all because they aren't secure. I've heard and read too many instances of people getting things hijacked and just don't use them.

My company has some good rules for working with data. No unencrypted copies of data, full disk encryption, don't take data home, make sure your devices are protected and encrypted, etc. Mostly common sense stuff, but making it policy makes it more real for everyone and enforceable. I don't have to like everything that's in place, but I certainly do respect it. The alternative is to bury your head in the sand and not believe anything bad can happen - until it does.