The Firefox phone
The Firefox phone uses the Mozilla Firefox browser as the heart of its user interface.
It's just a screen, as with the iPhone. It works with a pen, a stylus, or a finger. The interface can be adjusted so it's horizontal or vertical. Might I suggest running it on rechargeable AAA batteries?
It would have a hinged back that flips out so it can be laid on a table sideways. It would be rugged. It could come integrated with a version of the Thunderbird e-mail client, even the Sunbird calendar. Or choose something else.
You could even include a sync feature that copies everything inside the phone to its carrier's cloud, so no files are ever lost. You could set that to launch when it's plugged into a docking station, any PC, using a USB plug
The point is we all know how to use a Web browser, we're familiar with a pen interface, why not start there and work outward? The good folks at Mozilla have already done your branding. That fox at the top would make a great entry screen.
As to all the other whiz-bangs you might want, that's what they made AJAX for. I'm certain that, if Firefox were the Android interface, a special Google Mobile page, based on Ajax, would open that world right up.
LiMo, Symbian, and Android are all trying, in their own ways, to come up with a compelling interface for a mobile Web client. They should start the search by looking at what the open source world has already done in the mass market, Firefox.
And wouldn't it be ironic if a browser descended from Netscape actually did become the default interface the mass market needs to replace Windows?
If that happened Bill Gates might come out of retirement. I miss him already.