With the new Murano coming out in a couple of months I would be surprised if Nissan would also come out with a changed Xterra unless the changes are quite minor. My guess (and hope) is for a redesign in 2010 rather than cosmetic changes in 2009, then a redesign in 2011. Nissan needs to hurry with a third gen Xterra or they will lose market share. And I agree that it is important for Nissan to keep the Xterra rugged rather than making it some sort of gussied up Murano.
_Lazza
PS - not sure if a third gen Xterra would impact first gen resale value. The first gens have desirable attributes not shared with second gens (, and vica-versa). I suspect there will be first gen loyalists out there for years to come.