Microsoft said today that it has acquired online mapping services provider Multimap of the UK, a move it said “will play a significant role in the future growth” of its search business. Multimap will operate as a subsidiary of the Redmond giant, part of the Virtual Earth and Search teams in its Online Services Group. Terms of the deal were not disclosed. Mapping has become a hot category. Nokia and other companies have been making a big push in map-based services and applications. As we had noted earlier, Google Maps have proved to be a killer application on the iPhone.