After searching through the NCAA's frustrating websites, it appears to me as if they are ignoring the issue of the AP poll and just praying that it never disagrees with the BCS again. The best I could find suggests that 1) the AP awards a recognized title in football from 1936-present, and 2) the NCAA likes the AP poll enough to post it on its website, suggesting that there could, indeed be another "officially" split championship. They only list "BCS" after Florida in 2006, though, after listing every laundramat in Tuscaloosa for every other year.
I'll bet you that when the situation occurs again, however, that any team finishing #1 in the AP after the bowls will be considered as having won a share of the title even if they were left out of the BCS title game by most of the football world, just as it was with USC/LSU.