I knew someone would say that... See this thread
http://discussions.info.apple.com/thread.jspa?threadID=2464851&start=0&tstart=0
And also part of this one
https://forums.macrumors.com/threads/942301/
This issue occured on every mac I seen upon installing iTunes 9.2. I even tried clean installs of both 10.5 and 10.6 starting with iTunes 9.1 and moving on to 9.2. and the problem started directly after 9.2. The artwork appears fine in the finder within the iTunes music folder, but I you copy a file to the desktop for example, it's gone.
Wow....I never noticed that. The Finder not showing cover art has been driving me nuts!!
-Kevin