While I'm still waiting for my Wave invitation, Google released today code for the wave protocol with installation instructions to create your own wave servers, and how to generate a Self-Signed Wave Federation Certificate

The open source Wave Federation Prototype Server is delivered as a Java application that conforms to XEP-0114, the Jabber Component Protocol. In the examples below we show how to install the Wave Federation Prototype Server as an extension to the Openfire XMPP server, but it should run against any XEP-0114 compliant server.

The wave protocol specification draft defines Google Wave as a communication and collaboration platform based on hosted conversations, called waves. A wave consists of XML documents and supports concurrent modifications and low-latency updates between participants on the wave.

The wave federation protocol enables everyone to become a wave provider and share waves with others. For instance, an organization can operate as a wave provider for its members, an individual can run a wave server as a wave provider for a single user or family members, and an Internet service provider can run a wave service as another Internet service for its users as a supplement to email, IM, ftp, etc. A decentralized architecture that makes Google wave implementations limited only to your imagination.