According to the Wall Street Journal, Google is set to announce a set of software and services for mobile phones in the next two months. The service will provide search, Gmail, Maps, and YouTube.
Note that Google already acquired Zingku and Jaiku, two mobility oriented web sites recently.
Will the operating system be OpenMoko? Not likely because they are talking to the HTC and LG. Or just some Java Mobile Edition (J2ME) application API? More likely, but not the only option.
Obviously, the revenue stream would be advertising of some kind on the mobile.