I'm writing a book on naming your startup. Part of the process is checking for trademarks and secretary of state registrations. If you follow Silicon Valley (the hbo show) they actually dealt with this a few episodes ago.
I thought this article would be of use to everyone out there who wants to avoid trademark messiness. Hope it's useful.
I have an API that checks (and monitors) USPTO as well as 300+ social networks for name conflict. Use it for all new projects.