How to stop AppleIDAuthAgent flooding the console log with messages about expired apple id
This seems to result from deprecated MobileMe and iDisk preference files laying around. This post at the Apple discussion forum may help you delete the relevant files:

~/Library/Preferences/ByHost/com.apple.DotMacSync*.plist.lockfile
~/Library/Preferences/ByHost/com.apple.idisk*.plist
~/Library/Preferences/ByHost/com.apple.idisk*.plist.lockfile
~/Library/Preferences/MobileMeAccounts.plist
~/Library/Preferences/MobileMeAccounts.plist.lockfile
~/Library/Prefernces/ByHost/com.apple.coreservices.appleidauthenticationinfo*.plist
~/Library/Prefernces/ByHost/com.apple.coreservices.appleidauthenticationinfo*.plist.lockfile


Don't forget to close relevant applications (like Mail or Messages) before the deletion; it also might be a good idea to at least log out and in again afterwards.