Seems we overlooked it but, the source code for Google Wave Federation Protocol is already available! Check it out at http://www.waveprotocol.org

And, if you read the comments on http://code.google.com/p/wave-protocol/wiki/Installation it seems that this release is far from ready for serious deployment... There seems to be a need for developers to do some serious tinkering and help Google sort out all the bugs... So, if you think your qualified, download the source and start contributing to the Wave! Or, if you can't contribute to fixing the problems at least report all the bugs and glitches to Google so they can do something about it, you can post any issues you find here http://code.google.com/p/wave-protocol/issues/list