Question about cross-realms PVP

Hi
I would like to ask about cross-realm pvp.
I have recently seen that Lordaeron, Icecrown and Blackrock players has been queued together for BG
What about the arenas? Is it similar to BG where Icecrown players can fight against Lordaeron players or is it different queue?
Thank you for respond.

I would like to know too, I hope that the cross-realm is for bgs only and not for arenas considering the advantages that there are on icecrown and blackrock.

arena is cross-realm too, you can be on icecrown with your partner and play vs blackrock teams.