My friends and I found this last night when doing an 5...i mean 4-man.
We all had our CE droid out (you know, the droid pet that comes with collector's edition). We were trying to run past a pull, and they aggroed...ON THE DROID. Even better, they don't seem to attack the droid, so it's totally invincible! It didn't work every time, and seemed to work best on melee mobs. It doesn't seem to taunt so once you touch the mob it's yours.
To check this, I made a sith warrior and ran around korriban with lik 10 korslugs in a circle around the droid. ****ing awesome!