Chris Charabaruk, AKA @coldacid, is leading the charge to replicate Dan Zarella's Tweetbacks for Wordpress in Drupal. I'm hoping to help him out, as WhatTalent are interested in the module for a start. And so am I! =)
Take a look at the initial dev snapshot here:
It's marked as Drupal 5.x, but alter the info file and it should be fine for Drupal 6.x as well.