Google buzz, many publications write that people do not get Wave. They write that it is not widely adopted and consequently a "failure".
My answer to this is: "Wave is not ready yet!!". The idea of Wave is that it is a federated system defined by an open protocol, using open standards and published as open source.
Wave is alpha software, the protocol is not complete and the source is neither complete nor published. Wave is functional because it can be used. To some extend you can develop add-on functionality but realistically only for the published parts.
When Wave is functionally complete, when both the complete protocol and the source code are published it will be the time when developers and companies can start using Wave for real and make it their own.