From the recent Congressional hearings about credit card rates I read:
Levin's scrutiny of the industry has had an impact. JPMorgan Chase (Charts, Fortune 500) recently announced that the company would eliminate so-called double-cycle billing - which eliminates the interest-free period of consumers who move from paying the full balance monthly to carrying a balance. Additionally, it will no longer raise rates based on credit scores.
The day I see that I will stop posting on this site... I actually called chase to inquire about my 29.99 rate and I was told that they have no such directive. I guess they WILL do it in the future but not now as they have to suck up the sub prime debacle..