Well, a few days ago I ordered a Nikon F-mount to Canon EF lens mount adapter.I bought it from eBay for $22.90 shipped. It arrived on the 7th,and I had the opportunity to shoot a few dozen frames over about three hours' time, using four different Nikon-made primes on a Canon-made EOS 20D body. I shot most of my tests in Av mode, which is aperture-priority automatic in Nikon-speak. The adapter was finished entirely in bright metal,with no flocking or black paint or anything. China is my guess on its country of origin.
I put up sixteen snaps I did with the Nikkor lenses on the Canon 20D body,at http://www.pbase.com/derrel/nikkor_lenses_on_the_eos_20dday_1
Early results seemed pretty doggone good when using my 85mm,300mm,and 105mm Nikkor lenses. The jury's entirely still out on the 400mm f/3.5,which I shot for very,very few frames. The 105 DC seems to focus spot-on,and the 300/4 AF-S lens focuses very well manually,due to its long focal length and high magnification. Overall,I'm pleased with my first three-hour trial using this lens adapter. If it works as well as I hope, I think I'll acquire six or seven more, but I'll buy them from the discount retailers selling these adapters for $9.99 each.