As far as I've seen, burst is definitely the way to go in bgs right now - and destro definitely would hit that for you. As destro, though, you'll be running with the succubus or voidwalker out more than anything (if your battlegroup is anything like mine - it'll be voidwalker 90% of the time). The insta-seduce spec seems very appealing to me, personally, but soul link is also very important for any type of PvP. From what I understand, though, Fire and Brimstone is really not worth it in any spec; I'd go with a 0/11/50 spec for now, and pick up Chaos Bolt at 71. But if you want Chaos Bolt, I'd likely go 5/5/51 (extra Corruption dmg and hp).
One thing you ought to note, though, ALWAYS have a healthstone ready. And you'll be farming shards like nobody's business, because Soul Fire gets you some sweet crits. However, also remember that there's no dispel protection, so be careful when you get those Backdraft/Backlash procs they can be dispelled - and Immolate is also susceptible to dispels so Conflag can be hard to get off. Still, Shadowfury is your best friend as destro. Best for interrupts and getting away from melee (and getting away from melee is GOOD).