We use the Silverlight team's script that checks browsers against a list of what works and what doesn't. If you are saying that we could add Opera to that list, then I'll give it a shot and make the change if it works.
I use Channel9 with Opera since opera 9.5. I have to use the "mask as firefox" option though. There is really stupid browser check in channel9 and the main MS site. Still, silverlight.net has no such check and everything works out of the box.