Google has made no hardware announcements, nor has it given any indication that a gPhone is in the works. Google also has not given weight to rumors that it is developing an operating platform to enable more web pages, including Google’s, of course, to run natively on mobile devices.

But the company, clearly, is investing in the mobile space.

Last month, Google purchase Zingku, a startup that develops software to make it easier to share photos, messages and other content on smartphones. Then late Tuesday, Mountain View, California-based Google announced it had acquired Jaiku for an undisclosed amount.

Helsinki, Finland-based Jaiku makes a freely available mobile application that enables people to send short messages about where they are and what they are doing from a computer or smartphone, in what is dubbed microblogging. Jaiku competes with San Francisco startup Twitter.

There will be no disruption to existing Jaiku users, but the company is not accepting any new users for the time being. New users can sign up for an invitation to the service when we’re ready to expand, said Google product manager Tony Hsieh, on a company blog. We plan to use the ideas and technology behind Jaiku to make compelling and useful products.

Hsieh said the company had no definite plans to announce at this time, but that it plans to help drive the next round of developments in web and mobile technology. Google said it would be ready to provide some details of its plans for Jaiku within a few months.

In a Q&A section on Jaiku’s web site, the answer to why Google acquired Jaiku read: Activity streams and mobile presence are important areas where we believe Google can add a lot of value for users.

Jaiku’s software, called Jaiku Mobile, is currently available only for Nokia S60 smartphones, but a mobile version of Jaiku’s web site can be accessed using most mobile phones, including the iPhone. Users also can download the Jaiku widget, which is compatible with most Java-enabled phones.

The company was founded in February, 2006 and the online service was released five months later.