GreatFET is a next generation GoodFET intended to serve as your custom Hi-Speed USB peripheral through the addition of expansion boards called "neighbors".
GreatFET is designed to provide a significant step up in capabilities from GoodFET while making the design manufacturable at a lower cost than GoodFET. In addition to being designed for automated assembly, it can be hand-assembled with a soldering iron, though it is a more complicated assembly than GoodFET. An important similarity to GoodFET is that GreatFET has a USB bootloader in ROM, so it is possible to build a board by hand and install firmware onto it without the need of any external programming hardware.
Functional prototype hardware has been produced. Firmware is in progress.
For documentation and open source design files, visit the project wiki.
To join the project, subscribe to the GreatFET mailing list. This is the preferred place to ask questions so that others may locate the answer to your question in the list archives in the future. Additionally, you may want to join us in the #greatfet IRC channel on freenode.