welcome to the forum. if you're interested in OpekInkpot, i'm pretty sure the project is still active ; there is a forum here
about it and i believe most of the developpers (possibly all of them) are members here. if you are a developper, please stop by there, they might be glad to have some participation. in any case, you can certainly find out the latest news.
there are quite a lot of developpers around here so if you're interested in making new programs you might get some interest in collaborating. on the other hand, i would definitely not recommend you develop another file format. instead, what could be very useful is to develop either a reading application for the epub format, or (even more useful) a really good app for creating epub files, with a gui. we need those ! even an app which you could point to the repertory containing all the content, and tell it to generate the content.opf manifest and the table of contents ncx file would be very helpful.
but, i do strongly recommend that you support epub instead of creating a new format. it's the industry standard format, and is gaining a lot of acceptance among publishers, manufacturers and readers, but it's coming from a history of very fragmented offerings with many competing and incompatible formats available. the last thing we want to do is add to the tower of e-babel !
take a look around the site, and don't hesitate to ask any questions, you'll find we have a lot of very knowledgeable and friendly people here !
happy reading !