Thanks for all of the responses.
This hand surprised me a bit, because I'm usually pretty comfortable with pre-flop decisions, and I had no idea if a cap here was worthwhile. For what it's worth, I put CO on a JJ-AA, AK range, and I chickened out and called. Having read the responses, I probably should have gone ahead and capped. But what I lack in pre-flop agggression, I make up in flopping g00t:
Party Poker 5/10 Hold'em (10 handed)
converter
Preflop: Hero is UTG+2 with J[img]/images/graemlins/spade.gif[/img], J[img]/images/graemlins/heart.gif[/img].
UTG calls, <font color="#666666">
1 fold</font>, <font color="#CC3333">Hero raises</font>, MP1 calls, <font color="#666666">
1 fold</font>, MP3 calls, <font color="#CC3333">CO 3-bets</font>, Button calls, <font color="#666666">
2 folds</font>, UTG calls, Hero calls, MP1 calls, MP3 calls.
Flop: (19.40 SB) J[img]/images/graemlins/diamond.gif[/img], A[img]/images/graemlins/diamond.gif[/img], 5[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(6 players)</font>
UTG checks, <font color="#CC3333">Hero bets</font>, <font color="#CC3333">MP1 raises</font>, MP3 folds, <font color="#CC3333">CO 3-bets</font>, Button calls, UTG folds, <font color="#CC3333">Hero caps</font>, MP1 calls, CO calls, Button calls.
Turn: (17.70 BB) 8[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(4 players)</font>
<font color="#CC3333">Hero bets</font>, MP1 folds, CO calls, Button folds.
River: (19.70 BB) 3[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">Hero bets</font>, CO calls.
Final Pot: 21.70 BB
Results in white below: <font color="#FFFFFF">
Hero has Js Jh (three of a kind, jacks).
CO has Ah Kc (one pair, aces).
Outcome: Hero wins 21.70 BB. </font>