March is supposed to come in like a lion and go out like a lamb. So far, the weather in my part of the world has been more lamb-like than liony.

In mergers & acquisitions news, the climate swings toward the lion side of the scale. Twitter is the new proud owner of Posterous, according to its blog.

There’s a rumor out from SXSW, that CNN will buy Mashable, something Mashable is denying. I’m not linking to any of the news stories about the rumor. If it turns into a true story, with nobody lion about it, then I’ll amend the post.

Gowalla was bought by Facebook back in December. Its website now says “Thank you for going out with Gowalla. It was a pleasure to journey with you around the world. Download your check-ins, photos and lists here soon.”

I’m sure there’s more to come. March is far from over.