You can read some of our discussions around this topic at http://www.ashastd.org/phpbb/viewtopic.php?t=394
What we know is that most HPV infections clear naturally and don't usually recur way down the road unless someone's immune system is badly compromised. Researchers don't know for sure at what point someone is no longer likely to transmit HPV to a new partner, and for a number of reasons studies that look at this are difficult to do. Most of the experts we work with believe that when HPV-related lesions (like warts or cervical cell changes) are cleared for a number of months, the likelihood of transmission diminishes greatly. I think a number of them would say that while it cannot be proven, if lesions don't return over 12-24 months, then the risks of transmission are probably minimal. There's no way to put a more precise point to it, though, partly because there are some HPV infections that persist over a much longer period of time.
I hope this helps. I know the lack of a yes or no answer is frustrating. Please post again anytime you have questions.