Not sure how many people know about this but it could be useful for portal developers. On the SCEE PSP Development section they have some very nice guidelines for creating content for the PSP's browser or RSS Channel features. It also includes a few functions which the browser contains to get things like the PSP's productcode, firmware version and find out how the browser was started. You have to sign up but afaik you can just input fake information as they dont send any confirmation emails.
You can find them here