From the ROS blog:
I'm pleased to announce the release of ROS documentation and source code for the swiftnav_piksi package.
This package is a ROS release of a driver for Swift Navigation's Piksi RTK GPS receiver module. A pair of Piksi modules connected by a wireless link provides the location of each receiver relative to the other with accuracy as good as a couple of centimetres when there's a clear view of the sky. In addition, each Piksi module provides its location with typical GPS accuracy (about 3 meters). Often, one module is a stationary base station, which may optionally be located at a surveyed point, while the other is mounted on a rover and provides ROS navigation software with a highly accurate position relative to the base station.
RTK GPS has been around for a long time, however the Piksi devices hit a new low price point at under $1000/pair.
The documentation is at http://wiki.ros.org/swiftnav_piksi, and source and the standard github bug lists etc are athttps://github.com/PaulBouchier/swiftnav_piksi.