I remember reading somewhere (Joy of Home Brewing, I think) that the trub in the bottle of the brew kettle at the end of the boil (hot + cold break) contains material that the yeast needs to do it's thing.
On the other hand, I seem to be leaning towards the camp that likes it's wort clean.
So, some trub is required, question is: How Much? If I run the wort through a Chinois strainer, some would get through, is that enough?