[Orgmode] How to write an exporter

[Christian Egli]

Hi

I've been wanting to have an exporter for latex beamer and for
mediawiki. I thought that might be a nice summer project. How do I
write it? Do I use

 - the new mapping API
 - or the "new" exporter engine from Bastien which is buried away
   somewhere on a branch in git?

I guess the mapping API is included in org-mode proper but only gives
me access to the headlines AFAIK. What is the status of the exporter
engine from Bastien? Is it ever going to be resurrected?

Thanks
Christian