Vivisimo just launched Clusty Mobile, a cellphone version of its "cluster" search engine that's optimized for mobile Web browsing, according to MediaPost.

The engine is designed to minimize the amount of typing, or "keying," you have to do on your cellphone's keypad in order to get the information you want.

There's no word yet from Vivisimo on how to access Clusty Mobile. Keying in www.clusty.com brought up the desktop page on our test cellphone, which took forever and looked strange, and trying clustymobile.com gave us an error.

Even if they eventually decide to tell us how to get there, Cluster has an uphill battle, given the amount of resources the big names (Google, Yahoo, and MSN) are throwing at mobile search.

Vivisimo Aims for Mobile, Site Search [MediaPost]