not possible for nikon body to use canon lens, canon uses 7 or 10 electrical contact points to control the lens. critical factor here lies in the fact that there is no manual apertual ring on canon lens. also the focusing distant info cant be communicated to the nikon body, but nikon flash system needs this info to cal. its light out put.
but canon body can use a adaptor ring to mount nikon lens because nikon lens has the manual apertual ring. so the lens basically function as a manual lens. there is no problem for canon flash system when using the nikon lens (=manual lens) even for the new e-ttl2 (will revert back to e-ttl if no focus distant feed back from the lens), e-ttl does not use focus distant to cal the flash light output.
pls note however, if using manual lens (be it nikon lens or otherwise) on canon body, the metering may be off by a few stop on some models (namely 30, 33, 5, 1, 1n) especially in spot metering mode. it may also be about 1 stop off in other metering mode. using diff apertual also affect the accuracy of the metering. i use a pratika 300mm f4 on D60 in eva meter mode. at f4 have to over expose 1 stop, at f8 it will be correct.
so important here if you so decide to use manual lens on canon body, do test shots, record all setting so you can "understand" the lens effect on metering.
if you are interested to know more on using manual lens on canon body, pls feel free to pm me.