Oh and I forgot to note that PayPal generally gives out way too much personal info. If you want to know someones real name, all you need to do is send that email $0.01 and it will be conveniently shown to you. I guess it would work for all emails you have (but don't know who they are) if they just use PayPal with the same email. Sometimes it's good to know the other parties name, especially if doing business, but it should be an option.
Best system I've seen is with WebMoney, where user have reputation score based on their activity amount, users can write about problems in their profile (and account owner can answer publicly) and you can set yourself what information is public and what is private. For example, here's account that Valve (and others) use to process payments: http://passport.wmtransfer.com/asp/certview.asp?wmid=362311291686
. It has a high business level, has been verified and ok'd to have real info via notarized documents (but still the actual information can be private) and complaints are public. This gives the option to the user to decide if he trusts the other party or not.
Maybe it's a cultural thing too, but both Europe and Russia have a history that makes people understand how important it can be protect your private information. PayPal system is really limited compared to WebMoney, but sadly it's only used mostly in Russia and other CIS countries.