There has been some talk lately of a Google Wave iPhone application (not the current web app) titled Waveboard. Waveboard is being developed by Dirk Holtwick and is, “a client software for Google Wave for both Mac OS X 10.5+ and iPhone OS 3.0+.”
Currently, the app has been submitted to the App Store (a few times) and is waiting approval. Below is a video demo of Waveboard for the iPhone. You can follow the progress of the app on the developer’s blog – www.getwaveboard.com