Phonegap is an open source compatibility layer for mobile development.

It provides access to common mobile functionality such as geolocation, sound, contacts etc via a JavaScript API

I have just got the new gphone, the G1 which is a collaborative venture: google provide the OS, HTC make the hardware, T-Mobile provide the netwwork, and loads of software is written by many people - and made available via Google marketplace.

While a few things feel a little beta still; on the whole it all hangs together very well indeed.