http://www.openmoko.org/
This is basically a completely open source Linux based phone solution. It's still in the early stages, but looks pretty interesting, especially given how Apple has built the iPhone to not allow third party applications. They have a development preview device available for $300, and a full dev kit for $450 (includes JTAG dev board).
As a fortunate coincidence, the OpenMoko software platform also runs on the HP hx4700, which is the handheld I own and started gathering the necessary parts last week to load Linux onto (see http://www.handhelds.org/projects/hx4700.html for more info). That said, I should be able to do some dev on that device, which would be portable to the OpenMoko phone. They also have a QEMU based emulator.
Looks like it has alot of potential, although probably limited to the geek crowd. As some random forum comment noted, Apple sold more iPhones in the first weekend (half a million) than will EVER be sold of this device.
