Wave in the Cloud…
The Google Wave preview is worth the time to check out. My take, like many others, is that Google Wave is clearly aimed at Microsoft Sharepoint and Exchange. There are many cloud versions of Sharepoint-like collaboration tools already. As companies get more comfortable with their corporate email, they will be looking for the 1-2 punch offered by Microsoft and now Google. I would expect these two giants to continue to slug it out in the cloud application space. It may be just a matter of time before Google swallows Salesforce.com. If that does in fact happen, the fireworks will fly.
The best concise overview of Google Wave I have found is @ Mashable: Testing Google Wave: This Thing is Tidal
Update
Another great read on Google Wave and Microsoft @ TechCrunch: The Manhattan Project.