With Oryx, it is possible to create and share BPMN models. You can also discuss and improve it within the same working environment.
Moreover, the people from processWave (a group of students experimenting with ways to bring business processes into Google Wave) have gone one step further and integrated Oryx with Google Wave . Thanks to this you can see the actions of remote users just as they are being performed. See the video for more info:
This is the second business process modeling editor for google wave (that I know of). We already mentioned Gravity from SAP.