Jaiku launched in July 2006 with a mobile micro-blogging service similar to Twitter. Such services allow users to inform friends of their activities at any time.
Tony Hsieh, a product manager at Google, wrote in the official Google blog: "Although we do not have definite plans to announce at this time, we are excited about helping to drive the next round of developments in web and mobile technology."
Some commentators have speculated that the service could be integrated into Google's proposed G-Phone mobile operating system.
Jaiku founders Jyri Engeström and Petteri Koponen said that the service will continue to run normally and that Jaiku users will still be able to invite new friends.
However, new user registrations have been closed for the time being "in order to focus on innovation instead of scaling".
Jaiku employees will be transferred to Google and will continue to work on developing the service.
Jaiku is the latest in a string of recent acquisitions by Google. Last month the search giant acquired mobile social networking platform Zingku, also for an undisclosed amount, and recently picked up video game advertising firm Adscape Media for $23m.
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