According to the post:
Steve Jobs replied to a user asking for better PDF management through folders and said the feature is “coming”. Seriously, that’s the only word in the email. We can’t verify the headers of the email and MacLife.gr has no track record of previous Steve Jobs email-related material, but we think this one’s legit.
This is great news for those that use iBooks to gather a lot of PDF documents, or keep a lot of eBooks on their device. Being able to group them will certainly add to the functionality.