The unreliability of twitter got too much for me on June 27th , I've tried jaiku, friendfeed, pownce and plurk but ended up setting up my own microblog at http://microblog.weloveit.info/ using Wordpress with the Prologue theme.
I find it better and am actually posting more , its also more personal and I don't worry so much about creating noise for the people who follow me.
I've found that by reading peoples twitter feeds in an aggregator I can get a more coherent picture more quickly.
The best part about twitter was the Instant Messaging interface and the 'track' facility , both of which are currently offline.
The future should be more distributed not reliant on a single service provider.