Beginning tomorrow (September 30), Google will send out 100,000 invites to Google Wave. The product has received a lot of buzz, both for being innovative and not quite ready. Actually, Google admits it's not ready for prime time, which is one of the reasons why the invites are limited.
If you're not familiar, Google Wave is a collaborative tool that features real-time features. They're still working on features, including group definitions, draft mode and permissions.
Those who can expect an invite are developers who participated in an earlier preview, the first people to sign up for invites and select Google Apps customers.