Microsoft today signed a deal with infoUSA to license its business listing database. This will bring 13.5 million U.S. businesses into MSN Local Search and Windows Live Local Search — a significant data boost that will complement the new feature set and usability enhancements of Windows Live Local announced yesterday (see previous post). Microsoft currently has about 13 million listings from Amacai, and the additional infoUSA data will be integrated over the next few months.

In this way Microsoft is covering all bases on the data front (a non-sexy yet vital backend component to any local search site) with an up-to-date listing database. Add to this the capability for businesses to add and update their own information, and the social media layer that will be built on top of listing data (not to mention the imagery, traffic data and mapping interface), and you have the makings for a very robust local search experience.