A few years ago Hyundai brought a concept named the Portico to show. They have been developing it and hasn't received much publicity. From the spy shots it looks to be about Santa Fe sized with third row seating. It reminds me of a Mercedes-Benz R-class or Chrysler Pacifica which is the only two vehicles I can think of in that segment.
Another possibility is a few years ago when Mitsubishi was testing their Endeavor the spy photos looked a little wagon-like and then in production came with a beefed up suspension. So this could possibly be a new Santa Fe or Veracruz - but this is very unlikely.
Hyundai has been void of a mini van for 3 years now and in my opinion desperatly needs to fill this gap in their model line-up. Atleast here in Utah where there are generally big families, I have people coming in looking for a NEW vechicle in competition for the Toyota Sienna and Honda Odyssey but end up leaving when I show them a used Entourage. The Entourage is a great mini-van though.
The confusion for me is this vehicle was a concept in 2006 and was supposed to debut in 2010 but has not yet arrived in any market. From the spy shots I can tell it will have the family design language "fluidic sculpture" so perhaps Hyundai is waiting untill more models are introduced with this styling. We do have some pictures of the interior as well but not much can be determined from the limited veiws. Stay tuned for more detailes as they come.