It seems all of the guides to "lower your credit card interest by asking!" seem to rely on the threat of leaving for another card. Now that credit is so tight and everyone is trying to reduce their exposure, this threat doesn't seem to carry nearly as much weight as it once did. Has anyone successfully negotiated lower rates recently? If so, how did you do it?
Now that I'm making headway on my debt, enough that I should get a big bump in score soon, I want to give this a shot myself. I'm hoping something along the lines of, "Well, you are my highest-interest card at the moment, and I have enough money to pay the rest off...but if you lowered my interest rate, I'd gladly go attack another card!" will possibly get me a little love. I'm more interested in hearing your own successful tactics, though, because I have doubts about my thinly-veiled threats. 
Im curious. Did this strategy work? How is your overall payoff going?
TU Starting Score (09/23/10): 682 | EQ Starting Score (09/23/10): 697
Believe it or not . . . I recently called BoA and got a rate reduction from 13.24% to 11.99%.
Backstory:
I had a 6k BT (CL 12.5), that was scheduled to begin accruing interest after the 12 mo. 0% introductory rate.
My interest rate was 13.24%.
I had been paying the balance off at $500/mo. (4x the min.).
I didn't threaten. I simply did as you suggested. I told him that I could txfr the balance now but if they would lower the interest rate, I would allow BoA to make a few months interest.
He went away for a minute, then came back and said; "Yes, I see that you are paying the account down aggressively and we would be happy to offer you the lower interest rate of 11.99%.
They did and I paid it off the following month anyway . . . . LOL