We will expand upon the 200K lines of code we've already open sourced (detailed at waveprotocol.org) to flesh out the existing example Wave server and web client into a more complete application or "Wave in a Box."
This project will not have the full functionality of Google Wave as you know it today. However, we intend to give developers and enterprising users an opportunity to run wave servers and host waves on their own hardware.
"When released, Office Web Apps will be free to consumers, but organizations wanting to use them may need to consider beefing up their infrastructure to support SharePoint 2010."
Apparently, Microsoft's answer to Google Apps will be front-ended by SharePoint 2010 for "Active Directory integration, auditing, compliance, etc." [Consumer-level access will be via Windows Live on the Web.]
"The Ubiquity XForms processor allows developers to use XForms markup to create interactive web applications. Ubiquity XForms adds new APIs to a number of popular Ajax libraries, making XForms processing available in standard browsers, without the need for a download. "