My take

Essentially anyone who doesn't have their own mobile OS has joined the Google open handset alliance and those who have an OS didn't.

Several handset manufacturers jumped in and that makes sense as now they'll be able to produce their own handsets without licensing fees for Symbian, etc.

The real question is can a beta company (Google) produce a version 1.0 product and keep it going in a product form that consumers around the world will use? I'm guessing that the only reason this has come to fruition is that when Google acquired Android they've kept them as an operating unit and didn't toss them into the mess that is the Googleplex. I've been there a few times and the only way to describe it is that its like being at a university, but less productive.

Palm isn't in the alliance, and they've got a closed OS, but always have had a killer developers kit for the Palm OS. Granted, the Palm OS is getting a little long in the tooth and is sorely in need of being replaced, but the number of apps for the OS go beyond any other mobile device out there.

Being Google, one also has to assume that the OS will be heavily tied to the network for services, but will revenue come from those services? And will it be direct (from the handset user) or indirect (advertising, etc.)?

Time will tell.