As far as I understand it is possible to sync the iPhone app with the Mac Desktop version of Tweetie? So you don't have to read tweets twice (or have to scroll through the timeline to find the last read tweet). But I'm not running a Mac!
I was using Echofon for a short period because the developers provide push notification and, yay, sync between Echofon for iPhone and Echofon for Firefox. I bought Tweetie 2 some hours ago, because I like the style and the handling - I think Tweetie is the coolest Twitter-App out there. But I truly miss the sync feature.
So please do all Win users a favour and produce some Firefox plugin.
P.S. This topic could be merged with those two topics:
http://getsatisfaction.com/atebits/to... and
http://getsatisfaction.com/atebits/to...