What does blocking refer to in relation to floor joists?
Blocking typically refers to the structure that prevents the joists from twisting, which would be a concern over a load bearing beam. A solid piece of wood, often the same material as the joists themselves, is installed perpendicular to the joists without any gaps (e.g. I joists would use a piece of I joist for blocking). Two 2x4's installed in an X could also be done, and I've seen that with engineered joists, but check with your local building codes to be sure it complies.

I could also see blocking refer to additional vertical members (2x4's) to carry the load from the beam up to another load bearing object above the floor (e.g. a column). The last type of blocking I can think of would be fire blocking to prevent fire from traveling through the ceiling between parts of the home, though it's unlikely you'd see this requirement in a single family structure outside of a garage.

Like Tester101 says, call the inspector and ask for clarification, they should be happy to provide it.