Engadget has posted the hands-on with the app which - like Google's other service-specific iPhone offerings - is a browser-based web app rather than downloadable from the App Store.

The initial roll-out of Google Wave could be as soon as next month (30 September seems to be the date that keeps cropping up).

Wave is designed to be a ground-up reinvention of the way we communicate and collaborate. Think instant messaging, but with the open platform potential for plugging in Twitter and other methods of communication, too.

Lars Rasmussen, Software Engineering Manager, explains that a Wave is " a single shared space where two or more users can exchange real time dialogue, photos, videos, maps and documents in what we call a Wave. Everyone can reply to a Wave, people can come and go and you can drag and drop information from all over the web."

The hands-on shows the Wave dynamically updating between the desktop and mobile versions of Google Wave.

We previously brought you a complete guide to how Google Wave could change the way we use social networking apps and sites on the web: How Google Wave will bring together all your social apps