Seconded : But they really don't emphasize the possibility in their main materials.
The way I found to get on the program is to apply for the standard account, and then apply for the change to micropayments. In my case, they didn't tell me whether I was approved, the only way I could see that is by looking at their take on transactions.
Click on 'Pricing' then scroll down and expand 'Micropayments'
It's 5% + $0.05. So for your $1 in revenue only $0.10 is taken by Paypal.