Actually it does. Maybe it relates to exchange, just a guess why some would experience this issue & others would not. It only happens when you've send a file to someone & then try to empty that file from trash. As long as Mail is open it claims it is in use. I've notice various issues like this revolving around quicklook, I suspect the issue is related. Apple should make it so quicklook can never designate a file in use.
5/14/10 at 1:21pm