While much key information about the details of iBook development and distribution have remained cloaked by NDAs and limited to key partners, macrumors.com provided a useful summary of what has been confirmed and also shared information about the supposed categorization of iBooks: Approximately 20 primary categories, and 150 secondary categories. The mention of an Erotica subcategory is interesting for those of us who have been following Apple’s rather capricious acceptance and rejection of iPhone applications in its App Store.

Many developers have cried foul when their apps were rejected or accepted and subsequently removed by Apple only to learn that their recourse is limited: Apple’s agreement gives it extraordinary discretion to determine what’s sold in its store. Last week the Electronic Frontier Foundation made public Apple’s iPhone Developer Program License Agreement. Will Apple’s agreement for the iBookstore be substantially similar, or will books get different treatment than apps? Will works published by large trade houses be able to skip past or receive preferential treatment in Apple’s review process? Or will all works with content that might not be suited to younger and more sensitive readers (to borrow a phrase from broadcasters) be unwelcome?

Stay tuned. More as the iPad launch date—3 April— draws closer.