This one was a request by glitch, but I've been adding to it on and off and it's grown into more than a conceptual script. This will linkify usernames for logins, link posts, journal posts, and poll posts. Normal chatter conversation and /me emotes are left alone.
Because Greasemonkey doesn't work in the sidebar (not sure about FF 1.5) this script is useless for that. If you have chatter open in a window or tab it'll work fine.
