Okay, so I'm going to go out on a limb and call these badly Photoshopped images of a rumored Nikon D10 DSLR faaaaaake (see all that nastiness around the D10 logo?). But that doesn't mean there isn't a D10 in the works. For one, there is a hole in their line up between the prosumer D300 and the pro D3-a mid-range, full-frame DSLR to compete with Canon's 5D (and hotly anticipated 5D Mark II). Also, there are references to accessories for a D10, and Nikon expert Thom Hogan (who's written a zillion Nikon field guides) says they've never deviated from naming policies. Finally there is definitely a full-frame war going on. So, still firmly in rumorland, a D10 is very possibly in the works-we'll probably know by Photokina in Sept., which looks more and more exciting. [Photography Bay, Nikon Rumors]
The fact is that film and digital sensors have different UV and IR sensitivities, the modern dSLR lens has been designed with the digital sensor in mind. Each individual photosite (pixel) in a digital sensor literally sits at the bottom of a well with a tiny micro-lens on top of it. As light passes through a lens, it crosses over and begins to spread out again in order to focus on the sensor plane. In the center of the image frame, the light therefore strikes the sensor head on, but as we get further out from the center of the sensor the angle of incidence becomes more oblique. Which results in poor quality and more chromatic abberation on older full-frame lenses that weren't designed for the digital sensor. Its also the reason the the DX sensor is well suited for the CMOS/CCD. There has been a lot of progress in lens design in the last decade and its foolish to think that buying outdated film lens is a btter investment compared to the modern DX lens.
Also, I own the new Nikon FX 24-70 f/2.8, and its amazing, its vastly superior to the Canon 24-70 EF-L f/2.8 lens I used to own. As far as the sigma 70-200mm, I would agree its better then the half-decade old Nikkor, which is rumored to be replaced with nanocrystal coating and VRII soon, but Sigma also produces APS-C sized lenses for cheap, and if price is an issue that's an option as well.