AutoTrader.com is paying a reported $500 million to acquire the assets of Kelley Blue Book. The deal is expected to close by the end of 2010.

On the surface, the acquisition of KBB is fairly straightforward. While AutoTrader provides its own research for consumers to value cars and check out reviews, Kelley Blue Book is the gold standard in that segment, which also includes NADA Guides and Edmunds. AutoTrader says it plans to keep the Kelley Blue Book brands.

The acquisition, however, has interesting angles. Last year, KBB added The Trusted Marketplace, a used and new car site that put it in direct competition with other car portals, including AutoTrader, with which it had a two-year deal to provide leads. That deal, which succeeded a similar arrangement between KBB and Cars.com, was allowed to end six months early.