dunno if it was fixed in 3.08 but when wotlk launched you couldn't hex [target=focus] or anything else, just your direct current target. so thats probably why you don't see too many macros like this.

if you use jamba it has some targeting macro stuff built in that would be good for this kind of thing. i never bothered hexing anything in pve, and in PVP i would assume its not great due to distance requirements and burning a GCD casting hex may not be great (dunno). you could do something like:

/targetenemy
/cast hex

and maybe even stick in say 2 TE's on one shaman, 3 on another, etc so they each theoretically target different mobs.