It's called the OpenMoko, a phone platform -- devices and SDK, both -- that is built on GNU / Linux software, and is open all the way across the board. The device is built from the ground up to be modified by its user base: Both the device itself and the software you load into it are fully documented. They want you to crack it open and have a good time with it. And yes, you can even (gasp!) replace the battery.
The device itself comes loaded with a 640 x 480 touch screen, 256MB of on-board flash memory, WiFi, a MicroSD card interface, USB 1.1 connectivity (I was hoping for 2.0, but oh well), integrated AGPS (!), Bluetooth 2.0, and quite a bit more. And with people hacking merrily away at it, the phone has the potential to become any number of other things. The basic, non-developer version of the phone is $300; the developer versions add another $150 to $200 on top of that depending on what versions you get -- not a bad deal considering the thousands you'd normally have to spend to develop for any phone platform.
One of the key selling points for the iPhone is the user experience -- how other phones or devices might do the same things, but they don't do them quite like this, or all in one place. In the same way, the OpenMoko is selling an experience, but one aimed at a totally different kind of audience -- the hardware hacker and tech lover. It's akin to one of those electronics or chemistry hobby kits that you used to buy for the kids at Radio Shack -- instead of building a transistor radio, though, you're starting with a multifunction device which can be expanded out into any number of other things. The question, though, is whether that's a large enough market to be sustainable: They have to sell enough units to justify their manufacturing costs.
Also, how useful is the OpenMoko as a phone, especially in the United States? That part's a big unknown until people actually take it out into the field. The phone uses 2.5Ghz GSM, CSD, and GPRS, so it'll talk to most networks -- but many carriers get antsy when you try to bring in a phone they didn't sell you, and may charge you an activation fee.
And unless the OpenMoko is something the cell providers start selling in conjunction with their plans, layfolks are scarcely likely to even know about it. Few people want to go through the hassle of dropping $300 for a phone they've never heard of with no guarantee it'll even work on their network, for reasons that are wholly abstract. (File under: "So, uh ... what's this Linn-icks anyway?")
Would I get one? If I hadn't already just bought a phone, very probably. And, irony of ironies, the phone I use now was given to me free by T-Mobile when I renewed my service contract -- which right there says a great deal about how much of a hill the OpenMoko folks have to climb. In the meantime, how about a catchy ad campaign? Something like: "OpenMoko. It's not just wireless. It's string-less."