The Raspberry Pi is a tiny $25-$35 Linux-based computer that's been designed to make programmable devices more accessible, with a view to having them everywhere from schools to the home. It's potentially a lot more than a simple educational tool, though — it's capable of handling 1080p video and graphics that Raspberry Pi Foundation board member David Braben (of Elite development fame) describes in an Edge interview as "quite a way beyond Quake III Arena." The foundation believes that the proliferation of easy-to-use but expensive devices such as modern PCs and game consoles has made people a lot less willing to experiment with computers. The hope is that creating an inexpensive, small (about the size of a credit card) device will open the doors to people who otherwise wouldn't have considered learning about the way computers work.
The device has a 700MHz ARM processor, 128MB or 256MB RAM depending on configuration, HDMI and RCA video outputs, and SD card storage, with power coming over a 5V Micro USB connection. It's designed to plug into a TV, and you should be able to do most everyday computing tasks from there. After more than five years of planning and development, It looks like you'll be able to get your hands on a Raspberry Pi soon, with main production due to start next month.