Apple and the publishers are still negotiating over how to manage customers' credit information. Steve Jobs has decided to limit the publishers' access, only giving them basic opt-in information such as names, email addresses, and home addresses.
Publishers are dissatisfied with the 70% cut they will receive from sales, but they are more concerned with billing information. They want access to billing info so they can assess their demographics, and target their advertising accordingly.
They also have a hard time acquiring advertisers when all they can tell them is the number of downloads, but not the demographics. For example, a luxury car company won't want to advertise unless they know there will be wealthy customers downloading the publication.
Another disappointment for publishers is the inability to sell print/digital bundles. Without access to billing info, their print and digital offerings have to be sold separately. These stagnant negotiations are leading publishers to look at Android tablets. Their hope is that when Apple sees Android getting all the tablet-magazine action, they might be willing to revise their terms.
source: All Things Digital via SlashGear