I'm not familiar with the term p-to-p (other than peer to peer, and I don't think you inventing in bit torrent.....).
Heh, is peer-to-peer, but lending (money, not files). It's been around a number of years, working off the Kiva model, if you know Kiva (which is a charitable thing in which large groups basically make personal microloans to needy people around the globe).
The idea is that people can submit their details and request a loan, a site does an initial review, and if acceptable, offers the loan to members at a particular rate over a particular term based on the prospective borrower's credit score, credit utilization, income, etc.
Then, the loan goes up on the site and investors can look at the details, ask the borrower questions and choose to invest or not, in increments of $25.
Generally, the rates are lower than they'd be from a bank and the loans are easier to obtain in the current climate. Most people prefer that the interest they're paying goes to actual people rather than a megabank and from the investor's side, people can pick and choose who to invest in, at which risk level (excellent credit scores, low utilization, etc., have lower interest rates, lower risk of default), and their investment goes to help real people who need the money.
There is risk, borrowers can default - the sites will go after them but ppl declare bankruptcy and etc., and you can lose your investment in them. Also, your money is not liquid. You get $ back every month as liquid, but it's paid back in the fractional amounts per investor, so you get like cents back per loan - though it adds up if you have a bunch of loans.
There's also a trading platform, to sell your shares in the loans to other borrowers, should you want to liquidate.
Anyway, there are a couple of big companies been doing it if you're interested.