By now, though - and certainly once The Avengers is finally released in the US - the general public will immediately think of Samuel L. Jackson when it hears the name "Nick Fury" ... which creates a small problem for selling comics (hey, who's this frakking white guy?).
In fact, Marvel used the likeness of Jackson for the alternative Ultimate Universe version of the character some years ago, before any of these movies were made. But that doesn't help make the main "616" universe accessible to new readers who might wander into a comics shop after watching some of the movies.
Enter a new character, Marcus Johnson, who turns out to be the orginal Nick Fury's illegitimate son. Johnson was, in fact, named by his (obviously black) mother "Nicholas Fury, Jr.", and the "Marcus Johnson" name was to protect his true identity. He's now reverted to his real name, shaved his head, grown a beard, and ended up looking like ... well, Samuel L. Jackson. So, Marvel now has a new Nick Fury character, with Nick Fury, Sr., being shunted gracefully into semi-retirement (like many of Marvel's characters, he's incredibly old anyway, though until now he's been kept fit and relatively young by a special life-extending chemical formula).