TwitLook is a Outlook 2007 add-in that lets you access Twitter.  It is not quite to the point for public consumption, but it's getting there.

 Update: 5/2/09: You can now download Twitlook! No source yet - lots of ugly hacks as I learn my way around WPF. I'm also assuming you know how to install and Outlook Add-in manually via the Outlook Trust Center --- Tools->Trust Center->Add-ins. List of issues at this time (and certainly not the only ones)...

- Your Twitter password will be saved to your local AppData folder in clear text
- The Refresh process seems to check out if you put your machine into Sleep or Hibernate.  
- There is about zero error handling right now. I know, I know.... like I said, I was banging around more interested in getting stuff working.
- You can post new updates from the client.  They will be reported as if you had posted from the Twitter web site instead of Twitlook. Something wrong with the 3rd party Twitter wrapper code I am using.  The dialog for updating does not handle all of the different types of keystrokes very well right now.  It posts fine, but can be a bit of pain from time to time.
- When you do update, the TweetList does not update automatically to show your new update
- No DirectMessages
- No Reply unless you type it
- No tags, searching, etc.

Pretty much view and do updates…