nokia 770 sdk
yes, this has been covered heavily. not nearly enough noise has been made about how easy hacking this device is. nokia has opened up almost everything even placing the graphics under a creative commons license. nokia has also constructed a firm foundation to develop on. underneath everything is a debian based system with a 2.6.11 kernel. debian is one of the largest binary distributions mainly because of its apt package management system. apt will make it really easy to get new software and keep the installed software updated. a modern kernel means the device will be able to keep up with developing technologies like bluetooth and usb. the next layer is an xserver.
the best news for you is that nokia has set up a comprehensive development site. it describes the underlying software layers and how to set up the development environment to emulate the device. it even has a walkthrough for how to port applications to the device. as an example they show how to port gaim, which is funny because most places have reported that im support won’t be released until 2006.