We're coming out with a completely redesigned web site for 3.0, and we'll make that live as soon as 3.0 is released from beta. That site will have all of the themes available for download, and it will also have a page describing in detail how to create your own themes.

We chose not to bundle all of the themes with the application primarily because they're pretty big, and we didn't want to force users to download them all.

Thanks.