If shooting with a Nikon body but would prefer to use Leica R glass then take a look at this www.leitax.com for suitable adaptors. The designer claims infinity focusing and focus confirmation with Nikon F mount cameras but of course must use stop down metering.
Could be mouth watering with the new D3x body or wait for the inevitable D700x at a fraction of the price. We know that R glass works well on Canon full frame bodies so there should be no difficult optical problems as there is with many Nikon and Canon lenses when used "full frame digital".
The adaptors apparently come as kits including the difficult to find specialist tools to fit the lenses. A list of "adaptable" lenses are listed on the web site.