OK this has been discussed on many forums and maybe even here on NR, but anyway then one more time. Alright lenses are mostly listed in mm based on 35mm format except for medium format(100mm MF is app 50mm in 35mm format)
So then we have different DSLR formats giving us 1.5, 1.6 and 2.0 crop factor. and the argument is that the nikon 200mm lens is not 300mm on your D300 but 200mm cropped, but if you took a D3 with a 300mm lens both cameras would look close to the same if viewed side by side, yes I know the DOF is not the same.
This gets even crazier if you look at P&S cameras, my Fuji is a app 28 - 140mm zoom (5X Zoom) but the actually mm is 6.4 - 32mm. So when I sell it, I will not say to the customer that "look at this Fuji camera it has a 6.2 - 32mm zoom. No I would say that it has a 28mm wide angle start with 5 power zoom.
So in that same talk I will also tell people that they are getting app 450 mm from that 70-300mm Nikon Zoom on their new D90 camera together with their app 28 - 155mm effective zoom from their 18-105mm zoom. To me it is 100% irrelevant if you call cropping or extra mm, the end result is that the D90/300 etc takes a 12MP picture at 450mm effective, compared to 300mm on your D700, with the difference in DOF
I know lots of Nature Photographers using Oly gear for the 2.0 crop factor