The update thread says that Apple has said they need more time to review the app, so we can only hope that it will be approved soon.
The information can be found in this thread: http://forums.adobe.com/message/4377681#4377681
I also received this message after updating the Folio Producer tools to 1.10.1 (CS 5.0).
I've since uninstalled the latest version of the Folio Producer tools and reinstalled 1.9.1 but the folio I was working on is rendered useless (at least, from an iPad previewing perspective) until Content Viewer is updated.
Will now wait until the Content Viewer update is available via Apple and reproduce the folio using the 1.9.1 tools.
Tim
That's not a silly or obvious question (unless you've been using DPS for a long time). The answer is that Pro and Enterprise customers can download the v20 tools when they become available and begin taking advantage of the new features right away. For example, with the v20 release, publishers can create iPhone apps, which are already starting to be approved. Pro and Enterprise customers can use the Viewer Builder to create a custom version of the Adobe Content Viewer that they can use to test their v20 folios.
As I've mentioned, there is a "Publish As" feature currently in the works that eventually will let everyone publish to an earlier format (no earlier than v20). This should help mitigate the problems associated with the tools being released before Apple approves the viewer.
North America
Europe, Middle East and Africa
Asia Pacific