There's a very interesting story. The founders of Paypal, Max Levchin and Theil had studied the history of other failed digital cash, and concluded the reasons why they fail. The first one of them is that all the digital cash is too troublesome to use. The users have to download a software, and worried about the safety of their money.
Doesn't it look familar? Our bitcoin is far more complicated to use and keep safe than any of other digital cash. Yes, at the first, you have to learn how to find the damn $APPDATA%/Bitcoin to backup your wallet! And it's not enough yet because you have to learn TrueEncrpt! You have to Remember a very secure password which should be more than 12 letters long mixed with bla bla bla! And if you lose your money, all the monkeys on this forum will laugh at you, they will say it's all your fault and you will be like an idiot!
So please, the developer of the bitcoin client, make it easy and convenient to use for average merchants and average adopters. And the Paypal like service for bitcoin world is needed, too.