Just finished my first ConstantCon game using google+ and had a blast.
A recommendation for others playing on-line. One way to share a map in common with all players, aside from periodically holding up a sheet of paper, is to use a shared on-line whiteboard.
It worked pretty well for this session. There are several free sites offering whiteboards: we used http://www.twiddla.com which worked quite well. No sign up required, you simply go to the website and click on “GO: Start a New Meeting.”
The resulting page should include, on the right-hand side of the screen, a box that says, “Give out this link to invite people to this meeting” and a URL. Send the URL to the folks in your game and you can all visit the web page and see and edit the same sketch. No sign up, no password, no hassle.
The tool is not super-fancy, but it serves. And can be used for illustration of the action, as well.