I don't have much experience with PvPing in general, so take my comments with a pinch of salt and all that. But I'm assuming not many actually have much experience with PvPing with Brewmasters, and I at least have extensive experience with the spec, so I'll try to apply that knowledge to PvP where I can. I also did a small bit of PvP as Brewmaster recently, having to do the legendary quest. So y'know.
I would imagine we do more DPS than other tanks in PvP. Keg Smash in particular would be a nice burst damage ability, it's the majority of our damage in general. Hits multiple targets too, so y'know. From there, Jab is weak but builds up for Blackout Kick, which isn't too bad.
As far as defenses go though... Once you get stunned, it's basically over. I also felt just as squishy in PvP as Brewmaster as I did when I re-specced to Windwalker, but with Windwalker I could turn that squishiness into a strength via Touch of Karma. Which led to rather amusing situations.
I don't know if it'd be better if you stacked resilience, got into full PvP gear, etc. Specifically in response to your question about damage, I'd say we do more than other tank specs. We're probably squishier than the other tanks though, so it balances out.
Of course, if a more experienced PvPer comes in and tells me I'm full of shit, then please disregard everything I just said. :P