Google has taken to Twitter like the rest of the world and currently has over 40 Twitter accounts. The list of accounts seems to cover all aspects of Google and will continue to grow over time. On the Google blog site they state the following:
Like lots of you, we’ve been drawn into Twitter this year. After all, we’re all about frequent updates ourselves, and there’s lots happening around here that we want to share with you. Of course, we enjoy watching, and contributing to, the tweetstream (we hope you find our tweets useful, too). Because there are many programs and initiatives across the company, we’ve got a number of active accounts. Here’s a list of the current ones. We’ll update this list from time to time.
On their site they provide a list of all of their Twitter accounts if you would like to follow some of your favorites.