(from the FAQ)
"Can I Download Songs From the Napster Free Service?"
You must purchase songs to download them to your computer using the Napster Free service.
"Can I Really Listen to Napster Music for Free?"
Yes. Here's how it works. You can listen to every track in our 2,000,000 song catalog up to 5 times...
So it's not really free. It's just like Pandora or Last.FM but with a price tag. Misleading Slashdot title