I have been having a very annoying issue where messages sent from my iPhone (via my work Exchange server) show up as goobledygook in Entourage, though they are fine on the phone and indeed fine if I go into Windows Outlook.
Apparently this is a long standing bug in Activesync for Exchange server 2003 (but not 2007). Anyway, short of persuading IT to upgrade to exchange server 2007 (yeah right, they're going to do that for a mac user they don't want to support anyway!) there doesn't appear to be a good workaround but I did find an Applescript that will let you look at the message and then save it to the desktop and then you can drag it back into Entourage and delete the original. Clunky but better than nothing.
The script is found here. If I ever have time I might look at further automating the process of saving, re-adding and deleting via mods to the AppleScript or automator.