One of the little things that snuck by in the 2.4 patch notes is the ability to inspect players across factions. Horde can look at Alliance folk's gear, and Alliance can look at Horde people's gear. They can only do this when no one is flagged for PvP, however.
This is a really neat feature. My friends and I often times play "guess the gear" on the Horde toons we pass during our PvE adventures. We solve our arguments by looking them up in the armory, but now we'll just be able to right click on the Horde character's portrait and choose "Inspect." Pretty nifty.
Now... the real question becomes, where could this lead? For a long time players have been wondering if one day we'll be able to group across factions. Blizzard has obviously been leaning towards cross faction interaction and friendly support for a while now. We had the AQ gates opening, the recent goings on in the Isle of Quel'Danas, and lots of quests where you have to help out a member of the opposing faction.