Sony announced today on the PlayStation Blog
that "premium themes" for PS3 will be available on the PSN beginning tomorrow. Of course, "premium" means there will be a price to pay, and that would be $1-2.
The premium themes appear to be a little more artistic than the free ones the company has been doling out on a regular basis since the system launched. Sony states approximately 6-10 premium themes should be available a month and explains in the comments of the post that free themes will continue to be offered along with the premium content.