David Carradine has spoken. Yellow Book is the latest portal to agree to use Microsoft Virtual Earth for their mapping needs.
Search by product / service or business name and by location. They use AJAX to determine the location you're typing - which I love - start typing and a location result list offers you the options available based on the letters you've entered. They use WhitePages.com for their White Pages and Reverse Lookup search. White Pages is still using MapPoint Web Service. You can do a radius search by entering an address and selecting the radius distance. You can also get driving directions by selecting "details" on any given location and entering the starting address into the box. I actually like the interface they use for driving directions - simple, clean and intuitive with options for routing by distance or time and by text only or with a map. Oh, and this isn't just in the US - this extends out to their international sites, such as Yell.com.