Well, stuff like Touch of Murmur can't target your pet, the explosion hits him, but then it can't knock him into the air because pets are simply immune to being moved.
In the Kara Moroes fight, pets can't be garroted. In TK, pets are not targets for Wrath of the Astromancer, though they do take explosion damage, and they die very quickly to her arcane missiles.
Pets are also not valid targets for any boss mob I know of that randomly picks a target and focuses on them regardless of threat.
Edit: Pretty much, if the effect of the ability requires the target to specially react to that ability or wipe the group, a pet isn't a target. If it's just damage on something other than the tank, it probably can hit the pet.
Edited, Aug 28th 2008 6:55pm by Ehcks