Finnish microblogging service Jaiku has been acquired by Google (NSDQ: GOOG) for an undisclosed sum, according to an announcement on the company’s site. Like its main competitor Twitter, Jaiku allows users to share short messages and presence alerts with each other, using either a computer or a mobile device. A FAQ on the deal offers few details on the deal’s terms, saying only that Jaiku’s employees will be joining Google and that Google is interested in doing more with activity streams and mobile presence. Google had an early start with its 2005 purchase of mobile social networking service Dodgeball, but the founders left the company publicly frustrated earlier this year.

The acquisitions comes just a few months after Twitter raised its initial funding. Because neither that investment nor the acquisition price are known, it’s difficult to do a valuation comparison between the two. Of course, Google’s purchase is more than simply an investment, as it likely plans to integrate Jaiku’s functionality into a range of social and mobile applications.

• Twitter Raises First Round From Union Square Ventures, Angels