Ubisoft sells other publishers titles and has them on Uplay. If you buy an EA title on Uplay, you need to run Origin inside of Uplay, similar to buying an Ubisoft title on Steam. You would have to run Uplay inside of Steam. Fallout 3 required GFWL to run inside of Steam. I'm assuming that has been patched out, as many GFWL titles have patched that DRM out.
http://shop.ubi.com/store/ubina/en_CA/search/vars.false?q=fallout
This is the Canadian shop.
What I'm hoping for, is that I wont require Steamworks to run inside of Uplay. That crud (Steamworks) was added in mind when they made NV; I'm hoping it's been removed and won't be required for New Vegas; that Uplay's DRM will be all that's in and required in that version. I'm adding FO3 to that mix, because I'm not sure what all they've done to it since MS announced they were shutting down GFWL.
Or they can just put both of them on GOG, and make me a happy camper because I wouldn't have to worry about this DRM crud ever again for these titles.