I don't think multi-sig is functioning at the moment for XMR but it's a future planned feature. I could be wrong, and if so, please correct me.
No you're right, I had typed all in due time after saying that but figured I was about to start a monologue so erased it.
Although I am curious about what stage of development multi sig is in. Guess I'll go fumble around github after I take a shower.
Edit: I'm getting giddy just thinking about multi-sig being implemented into Monero in the future. I think I need to unplug for a couple days...