Moving from original iPad to new iPad (2012): Is a cover like Apple's black one available for the new iPad?
Targus is advertising iPad 3 cases and one of their portfolio style cases may suit you. 

Many iPad 2 cases will work with the new model. Although I haven't tested any of these on a new model iPad, you might consider: 

iLuv Portfolio Case with Stand

Filemate Imagine series smart cover

Beyond that, a search for iPad portfolio will produce a multitude of choices.