EDIT: I see PKM beat me to it with all the info there is, really!
Originally Posted by tron_
Best place to learn about the technical differences between the different Hasselblad lenses:
Other than the optical difference between the old 50mm and the FLE, the rest is pretty minor differences in body design. The older 50mm C lenses will all be non-FLE, weigh a little more, and takes 63mm drop-in filters (a little hard to find, I think, but some people find was to use 67mm filters). All the later versions will take B60 filters. The standard advice is to get the newest lens that fits your budget. The CF non-FLE's go for a lot less than the CF (FLE) lenses.