Isn't there a Growl plugin for Mail.app? I believe Growl alerts would still show up in fullscreen mode.
Thank you. You're right there is a growl plugin for mail. I've just tried it and it does show up on top of fusion in full screen mode.
I would'nt say it's exactly what I was hoping for though - When I'm not working within fusion, I would'nt want growl notifications of new mail. I'm much happier with the (less obtrusive) little number that appears on mail's dock icon as a mail notification method.
I suppose ideally what I'd like to see is something integrated within the vm, providing new mail notifications, for example in windows system tray.