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They have partnered with several European directories to offer local search through their toolbar, Thomson directories being the last announcement.
The search results highlight phone numbers and make them click to call accessible through Skype.
Being a VOIP application, it seems Skype has two ways to look at these listings (and they don't have to be separate, integration is possible):
1. Skype to eventually try to monetize results with a PPCall service.
2. Online phone book integration with your phone. Serve the results, let people click from their computers, and be the leader in bringing a more seamless local search experience for it's users.
I think there will a few different areas of interest, local being the one for discussion here but also financial and travel will be huge.
Local PPCall will probably be dominated by companies with 'feet on the street' as getting small, local service-based companies onboard will take huge resources. The number of advertisers will be the influencing factor on who wins in the local PPCall race as technology and other factors will play second fiddle to having relevant ads to monetise.
The other PPCall areas are likely to be dominated by companies that can get their ads on the sites with decent inventory as it will be relatively simple to sign up financial companies etc.