ASTwitterLibrary is a script that contains a list of methods you can call in your Applescripts to interact with Twitter. It's very easy to integrate and full instructions come with the download.

WHAT'S NEW
Version 2.1:
  • Fixed bugs due to API and website changes on Twitter.

REQUIREMENTS
PPC / Intel, Mac OS X 10.4 or later.
ASTL_2.1.dmg
Released on 2/11/12