Random little things off the top of my head:
1) the left hand collaborative notepad is an awesome idea, this is very cool. Maybe don't need line numbers in the plaintext mode though? Can't really tell what the other formats allow either, just syntax highlighting? Would maybe be neat if they were rendered in the appropriate formats?
2) Let us pay for it! No seriously, I want this to live!
3) Will there be logins or always just dynamic? Maybe save an email address in a cookie and use gravatars?
4) If using email addresses having a way to send the 'codepad' to all participants would be a good way to send out meeting notes / todos.
5) No kill/yank support in the editor! :(
That's all off the top of my head, but super cool! We'll try it out for our next team meeting.