So, I have been looking for a way to do this for ages. Update both Facebook and Twitter with one application or from one place.
I found Moodblast for my Mac but couldn't find an equivalent for my Windows PC. Finally I found twittersync (a facebook app) which updates Facebook from Twitter. As you can update twitter from any number of sources, web interface, mobile phone, IM, etc, this means I only have to update my status in one place (twitter) and it gets automatically copied to the other (Facebook).
Incidentally, I also found twitbin which displays a bar in Firefox through which I can follow my friends tweets or the public feed and update my status.
Update: Using twitterfeed.com you can have your Facebook friends status feed piped into Twitter. So, when using twitterbin or twitterIM, you get your friends Facebook status updates included in your twitter updates.
Update (again): OK, using twitter feed in this context is causing a bit of a problem. It is re posting all my friends status updates as my own. What is happening is the twitter feed is placing my friends status updates on twitter, which is then syncing these back to my facebook status (via twitter sync). Looks like its back to the drawing board!
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