i found this out half way through Beta, very handy. although now i just let Origin launch automatically when i click a server in Battlelog, since it's so much hassle to go: Steam -> Origin -> Battlelog -> play if people want to get hold of me while im on BF3, get on mumble.
I don't have any conflicts with both enabled. I do it slightly differently though. I've added BF3.exe as a non-Steam game and when I click on it, up pops the battlelog with overlay and then when the game launches it also has overlay. So all I have to do is click this and away I go. Plus it shows me playing BF3 instead of Origin for all you Steam freaks that want to keep everything proper.
I found this during the beta, and renamed origin in steam so it showed me as playing BF3. But I've stopped using it now as I always forget to close origin when im finished, and steam still says i'm playing.
I use Firefox. If Origin isn't already running, it launches Origin then brings up Battlelog. If Origin is already running, it brings up Battlelog. What? Why? How? What?
I trolled my friends using this - when the Steam workaround was first published I set the Origin app in Steam to 'Call of Duty: Modern Warfare 3 Pre-release'. My friends, being gullible MW3 loving people, thought that I really did have a copy of MW3 pre-release and that I was playing single player a few days before them. Now, with the actual release, I renamed it to 'Origin (probably Battlefield 3)'
You can do this with any game, it's not really adding the game to Steam it's just adding the shortcut - this is a nice feature but it's been around for a while. Still good to let others know