I think twitterific does.

weird, i have to open it to see updates...

You can get an app called Boxcar that works with Twitter and gives push notification

apparently iTwitter has "push=like" stuff...you could also set up growl on your mac and do it that way...

I use the growl method to get near real time...

nevermind... i think i found the setting to turn on twitterific push stuff, haha.... waiting for someone to tweet.

tweet

chirp...and, twitteriffic blows btw! Twitterfon is miles above, but dnt know about push notifications