I'm guessing that it was an accidental side effect. If it was intentional, they could have locked out the use of adb and unverified apps. Yet they didn't.

Still, I'm not very happy with the update. I understand what they're doing: they've made the social reading bit a priority and they are making marketing a priority. But the reader is lacking in other areas. I think that it's beyond belief that PDF support still isn't there because that is a big reason for choosing a tablet over an eInk device. The lack of support for library books is also disappointing since I would imagine that most of the people who are serious enough about reading to buy a dedicated ereader is going to read a mix of bought and borrowed books.