[brianprogrammer]

If you put a "Pay me a dollar just because you like my site" feature on your wordpress site you will probably not get many dollars. But since people are already comfortable paying small amounts of money via itunes and the app store it seems like a nice additional revenue channel, and probably leads to more site traffic, especially from the core fans.

As for the extra value to the user, no idea, maybe they can make it easier to submit comments? No ads maybe?