I've seen a number of times where people asked about controlling pets and I could be slow on this. I never noticed until after the 1.6 patch that there is a command in the keyboard bindings for "Command Pet". By default this is set to "y". In order to use it, you hold down the key and then left click on a target, rather than light attack, your pet(s) will rush forth and attack the target.
They seem to not switch either. For example I can send them to distract a melee mob while I focus on a healer.
Personally I found "y" to be too far of a stretch for retargeting them in combat so I switched it to "t".
The only downside I've seen, is sometimes my clannifear starts refusing to fight all together. I'm still monitoring this before I send a bug report because I don't know yet if it just sometimes happens, or specifically happens when commanding them to attack. Also it's noteworthy you can't command them to attack from horseback.
And so did many brave men, women, and beast fall to the end of Beta, never to be heard from again. All that is left, is whispers of the adventures they had.