So I got myself a pownce account thanks to an invite from Harish. My stream is here.
All this while I've stayed out of the twitter-tumblr-jaiku microblogging thing, but pownce was written in python+django, so hey, had to check it out.
Having checked it out, here is my micro review - Its pretty neat. I like the fact that it has private messaging, plus messaging within groups. Makes more sense than forcing all posts to be public like twitter. Pretty straightforward to get going, though others say that the twitter interface is simpler (haven't seen it myself). There is a desktop version too, but it requires Adobe AIR (Apollo), which sucks because no way am I going to install AIR just to use pownce. Plus there is no mobile integration.
It's still pretty new though, so I expect most of these things would be sorted out. At the moment, creating an account is by invitation only. I've got 3 more invites to give out, so if you want one, put in a comment.