List of official Google accounts on Twitter :

Google - Google’s main account on Twitter.

YouTube - For YouTube lovers.

Googleimages - For Google Image Search updates.

Googlereader - For news regarding Google Reader.

Googleapps - For latest and popular Google Apps.

App_engine - For Technical Updates on Application Engine.

Blogger - Acts like Blogger FAQS.

Googlewmc - Twitter account for Google Webmaster Central (main account)

Adwordshelper - main AdWords support account

Mattcutts - Matt Cutts, head of web spam team in Google

Are we missing any? Leave a comment!