I'm writing a WordPress plugin to create an eBook from a selected category in most major eBook formats. I would like to support MobiPocket since that's the format used by the Kindle but I'm not sure how to go about it. From what I've read .mobi files are actually Palm Resource Databases (PRC) but I haven't been able to find a PHP class to work with these.

I thought about using exec along with KindleGen but that would be undesirable as it would complicate initial setup. I've also thought about hosting a web service somewhere and using XML-RPC to accomplish this but that also complicates things.

My question is: is there a PHP class/library (PHP-only preferred) that can work with PRC or even better, a class that specialises in creating MobiPocket ebooks? (needs to be open source since I'm releasing under the GPL)

I've tried searching but haven't been able to find anything.