Google has just announced that after six months of keeping Google Wave in preview mode while it worked out significant bugs, that the real-time collaboration tool is available for anyone as part of Google Labs with a standard or enterprise Google account (i.e. part of Google Apps). All you need to do is go to wave.google.com and login.
It doesn’t seem that there are any major announcements regarding what Wave can do, although Google has apparently made some improvements in the API. Google has given some examples of how organizations have used Wave to date on this blog post.