For the record, I do not believe there is such a thing as excess starting pitching, therefore I do not advocate turning anyone into an extra in a Charlton Heston movie.
In 2009, most every NL team uses 6-8 starters more than 50 IP, and half use at least one more more than 40 IP.
9 - NYM, 9 SD (+1 > 40 IP)
8 - FLA, MIL (+1 over 40 IP), WSN (+2 >= 40 IP)
7 - Hou, LAD, PHI (+1> 40 IP), PIT (+1 > 40 IP), St. L.,
6 - AZ, ATL, CHI, CIN (+3 over 40 IP),
5 -Col (+2 > 40), SF (+1 > 40 IP)
Figure that between our top 3 teams (H'burg, Syr, and Was), you need 12 or so pitchers who will pitch a lot at MLB or AAA, counting guys who backfill from AA for AAA callups.