I was finally able to reproduce consistently a freeze that I've been getting reports on for a long time, so I think I finally was able to fix it. The issue was related to stopping playback / shutting down the app.
1.3.3 (06/22/12):
-Fixed bug where notification area does not hide when selecting the notification controls
-Fixed possible crash when changing tracks from remote controls
-Fixed some issues on first install
-Fixed issue where album art background would not change
-Fixed some shutdown issues
-Fixed issue where playback would stop if you changed orientation back and forth really fast
-Other stability fixes
1.3.3 (06/22/12):
-Fixed bug where notification area does not hide when selecting the notification controls
-Fixed possible crash when changing tracks from remote controls
-Fixed some issues on first install
-Fixed issue where album art background would not change
-Fixed some shutdown issues
-Fixed issue where playback would stop if you changed orientation back and forth really fast
-Other stability fixes