Yahoo is just going to charge fees in a few months
too.  It even says somewhere in there info that
it is free for now but fees will eventually
be charged.  Palpal is not being strict yet
with making you sign up for a seller account 
(I think they are worried about losing a lot
of accounts).  I think they make a lot of money
off of the float when people leave money in 
their paypal account and because they don't 
transfer the money for a couple days after
you withdrawal it.  If they are going to charge
and it is going to work they are going to have
to transfer all the money next day without a 
charge (which currently would be yet another 
fee you have to pay).  Sellers will just
stop accepting paypal if they insist on charging
a bunch of money.