As everybody has said, it's best to keep it out. However, don't sweat it if you get some (or even most) of it in the primary, everything will turn out fine.
Ever since I built one of these, I haven't had to worry about hop sludge. Now I just need a better approach to keeping break material out of the primary.
I ladel my wort into the fermenter 1/2 full of ice so I dont get that crap in it but my way is time consuming but it wont hurt the brew if it gets in there.
BierMuncher has a neat trick, where he puts his chiller inside a paint strainer, and racks clear wort from within. I may have to give that a try with the next batch. (His picture, not mine!)