Late to this party but I have some caution to express over metabilly's deletions.
To all intents and purposes Messages beta is iChat 6.1 (the Engine if you like, is iChat's)
Both of these will be needed by iChat when it is reinstalled. Not that it won't fetch all the Buddy pics again, but it will need the Jabber items in this folder.
The IMAgent one is also used by FaceTIme and could upset it's operation if this is deleted.
The same with the various .plists
The iChat ones include ones for the AIM logins, Jabber logins and the Subnet (Bonjour Login) which will be needed by iChat if reinstalled by the deletion (Uninstall option) of Messages.
There are also the Shared Library one (The Recent List is in here, also needed by iChat on reinstall)
Messages still uses the same com.apple.ichat.plist as iChat which holds all the Preferences you may have previously set for iChat in the Preferences (Everything except the Accounts pane) as well as some Menu items.
The Status Messages one is used agiain by iChat as well as Messages beta
Again the IMAgent.plist deals with FaceTime in Lion as well as iChat or Messages beta.
A simpler method of using the Finder > Go menu and holding the ALT key shows the access point to the Home Folder/Library The Library appears in the menu Drop Down) where you can choose the Preferences or Caches folders rather than using the Terminal.
Please, if posting Logs, do not post any Log info after the line "Binary Images for iChat"
iMac 2.5Ghz 5i 2011 (Lion 10.7.4)
G4/1GhzDual MDD (Leopard 10.5.8)
MacBookPro 2Gb (Snow Leopard 10.6.8)
Mac OS X (10.7.4),
"Limit the Logs to the Bits above Binary Images." No, Seriously