I searched a bit around, but couldn't find any thing like this.
In Shattrath there are two different locations for the battlemaster's joining area. One for Alliance, and one for the Horde.
The other day me and my 2v2 partner was standing on the alliance's area (I'm horde) and we had the longest queue we had ever seen. It was like 20 minutes for one round. So when we stood there, I started to inspect other hordes' arena teams that was there waiting to join the arena. Then I accedently clicked on an alliance player, and I could inspect he's Talent tree and PVP arena teams/HK's.
I did that while using an inspector addon, "Examiner". I tried to log out and deactivate the addon and wrote /inspect on the ally, same person, but it said "You cannot inspect that target". I relogged and activated the addon again, wrote /inspect and then the window popped up, and I could see his arena teams/HK standing and Talent Tree. I could not see his gear though, only the pvp/talent stuff.
Downloads; Examiner
Edit: I just recently found out; You can ALSO inspect player while dead with this mod Addon! =) We wiped on vasj last night so i figgured it while CRing to ress =P