Good advice so far.
A couple weapons like
this would make for much fun, just as an example.
Talents: There is really no reason to put a point in any tree but enhancement at this level. I was even 0/50/0 when I pvp'd a bunch at 59.
As for specifics, check the shaman faq, the build there for enhance hits the key talents, except that for pvp you may want to skip Enhancing Totems in favor of Guardian Totems (you drop lots of grounding totems in pvp), and I also prefer Toughness over Anticipation for pvp (for the reduction in movement impairing effects, one of our biggest weaknesses).
BGs: There is a good pvp guide on the o-boards for shamans.
Basically, your most important totems are poison cleansing (against rogues and hunters), grounding (against casters), tremor (against fear from priests, locks, and warriors), earthbind (to slow enemies when defending and/or when you dont think a fear is likely), and searing (little dps but it helps to keep rogues in combat and prevent restealth unless they blow vanish and, also, to prevent a flag cap if they sap you).
Don't be afraid to equip a shield when facing physical damage (like rogues, hunters, and warriors), especially when you are defending in WSG or AB and a rogue may get the opener on you. You will still do serious damage but survive (enjoy it now, late 60s and 70 you will be rogue food unless you have awesome gear, and even then . . .). A shield swap macro is key.
Otherwise, stormstrike, earth/frost shock (flame shock first on rogues to prevent vanish [at this level anyways, later they can cloak and vanish]), and purge, purge, purge.
Finally, get an addon that keeps track of your windfury, shock, and stormstrike cooldowns, like wf3sec, and visit elitistjerks.com to learn enhance shaman mechanics.
Enjoy. Enhance shamans are powerhouses in 60 and under pvp (they can still be effective later, but it requires much more skill and gear and luck and the alignment of the stars . . .).
EDITS: Fixing the link.
Edited, Aug 18th 2008 10:47am by lavagulin Edited, Aug 18th 2008 10:48am by lavagulin Edited, Aug 18th 2008 10:49am by lavagulin