Embedding Vaadin apps in Google waves is surprisingly trivial (sorry for the ginormous screenshot):
You need to deploy your app somewhere (eg. Google app engine works fine) and publish a simple
gadget specification that points at the app. After that you can just add the gadget by the XML URL to a wave.
Yes, the gadgets are displayed in a iframe anyway, so I believe (after a half hour investigation - I could be wrong) that this is the easiest way to do it.
Has anyone come up with some cool use cases with Wave + Vaadin? Would be nice to come up with some way to make use out of Wave’s way of interactivity. Share your ideas if you have some!