At first, I thought that you could secure the different "lists" (personal, professional) for different users. I would have use the public list to post to twitter and the "profesionnal" list to share with my colleague. That's really not that way. There are things that I don't want to share on twitter that I want to share on friendfeed so I have to maintain two different accounts. But, congrats to FF for the IM and remember that Twitter failed at it completly.

Maybe FF should market their product to clearly differenciate them from Twitter... giving more importance to private groups and small communities for example.