When I multiboxed, I used a druid to tank for my 4 shamans in some Heroics at 70, back when swipe was only 3 target max.

With the new changes, tanking mobs is even easier. As with any tanking class, you want all mobs in front of you. The reasons are different from druid to pally/warrior, but the necessity is still the same.

Unless you get adds, it is trivial to position mobs properly:
Faerie Fire to pull,
When they get to you, take 2 steps backwards.
Swipe like a maniac (throwing in Demo Roar and Glyphed Maul).