Just discovered TwitterFon twitter app for the iPhone thanks to @chasejarvis.... lots of features, free, no ads, more functional (IMHO) than my previous one (twitteriffic). Going to give this one a good go and see if it works as well as it looks. Oh, and did I mention it's free?
Matt Haughey (of metafilter fame) has a great response to the whole Twitter client thing:
http://a.wholelottanothing.org/2009/01/matt-whats-your-favorite-desktop-twitter-client.html
In short:
IT'S A TIMEWASTING FIRE HOSE OF INFORMATION.
Do what I do, which is every few hours if you're at a stopping point or bored or whatever, go to twitter.com in a browser. Scan through the missives from your friends, maybe page back a couple pages to catch up to the last time you checked. If you think of something you need to say, toss it up as a new message.
THEN CLOSE THE BROWSER TAB AND GET ON WITH YOUR LIFE AND WORK.