To get rid of the diacetyl in future batches, do whats called a diacetyl rest. It basically involves raising the temperature of your fermentation maybe 4-5 degrees towards the end of active fermentation. This helps the yeast to go back and clean up after themselves. A quick search for "diacetyl rest" in the forum here should turn up a few good threads about it.
Keg #1: Oatmeal Stout (WLP004)
Keg #2: Oatmeal Stout (WLP037)
Keg #3: Denny Conn's Bourbon Vanilla Porter
Keg #4: Empty
Bottled: Apfelwein, Scottish 60/-
On Deck: Simtennial Pale Ale