Based on multiple answers given by NextGen staff, it seems that NextGen has not started development on a native iPad app, nor does it intend to. This comes from inquiries to NextGen sales members, trainers, project managers, and engineers. No one knows of an iPad app in development.
What NextGen may be developing is a more complete version of their NextGen mobile, which allows web access to the NextGen database in a device optimized format. Currently NextGen mobile has limited functionality.
The advantages of this format is that it will be developed once, but available on an iPhone, iPad, any Android phone or tablet, and any windows based hardware. This disadvantage is that you would have to pay NextGen monthly access fees, as NextGen mobile is software as a service and resides on their servers.
I would prefer a native iPad app. The other devices they are tailoring to be compatible with, do not have the battery life to make them usable, and so far are not really any less expensive than an iPad.
There are talks of third parties developing a native iPad app, and I’ll keep you up to date on those developments. If anyone knows of a native NextGen app (not NextGen mobile), then please let me and everyone else know in the comments.