Google announced it will buy Jaiku, a Finnish web and mobile based micro-blogging service. Founded last year in February by Jyri Engeström and Petteri Koponen, Jaiku is targeting the teenagers that are already familiar with mobile SMS, blogging and IM clients.

Considered the main competitor of Twitter, a similar US service founded in March 2006, Jaiku has managed to differentiate itself by introducing the lifestream concept, a feed that shares your online activity with your friends

The terms of agreement between Google and Jaiku weren’t disclosed but in a Q&A section on Jaiku’s website the founders announced that the current users can still use the service as usual. Tough new user registrations have been closed for the time being.

In a blog post on Google official blog Tony Hsieh, Product Manager, explained that Google acquired Jaiku because the application can be used to help busy people to stay in touch with their loved one, regardless of whether they are at a computer or on a mobile phone.

But Hsieh didn’t provide any specific details on how Google plans to develop Jaiku’s applications.

“Although we don't have definite plans to announce at this time, we're excited about helping drive the next round of developments in web and mobile technology,” wrote Hsieh.

Two weeks ago Google bought mobile social-networking company Zingku a start-up that uses standard text and picture messaging on a mobile phone and a Web browser to facilitate the communication between its users.