Im using a PVP mutilate aswell (Was using Combat Daggers for raiding before), its pretty nice in PVP, good combo point buildup and envenom hits pretty hard aswell (critted around 4k I think), and is pretty good on armored targets.
Trouble is that its largely Crit based, and with all the resiliance out there now that makes it less viable.
There is a combat mutilate version that is prolly better in that regard, and also better for raiding, but you get gimped stealth and some other downsides on that.
I got no resiliance at all, so I really got to pick my fights in BGs (naturally I dont, I jump on the closest target like a maddened ferret, but I SHOULD), as far as PVP gear goes I only got 2 of the main hand daggers (slow 90ish dps, for mutilate obviously) so far.
Q6700, Abit X38 QuadGT, 8Gb (4x 2GB) OCZ Reaper DDR2 1066MHz, Gainward GTX 285 1Gb, X-Fi XtremeMusic