Twitter and Posterous announced that the former has acquired the latter. Terms of the deal have not been disclosed, but we do have official announcements from both companies.

If you use Posterous Spaces, don’t freak out just yet. It’s not being shut down – at least for the time being.

Twitter writes on the Twitter blog:

Today we are welcoming a very talented group from Posterous to Twitter. This team has built an innovative product that makes sharing across the web and mobile devices simple—a goal we share. Posterous engineers, product managers and others will join our teams working on several key initiatives that will make Twitter even better.

We’re always looking for talented people who have the passion and personality to join Twitter. Acquisitions have given us people and technology that have enabled us to more quickly build a better Twitter for you.

Posterous writes on the Posterous blog:

The opportunities in front of Twitter are exciting, and we couldn’t be happier about bringing our team’s expertise to a product that reaches hundreds of millions of users around the globe. Plus, the people at Twitter are genuinely nice folks who share our vision for making sharing simpler.

Finally, we’d like to offer thanks to all of our users, especially those who have been with Posterous since day one. The last four years have been an amazing journey. Your encouragement, praise and criticism have made us better. Thanks for that. We look forward to building great things for you over at Twitter.

Good move for Twitter? For Posterous? Let us know what you think.