Basically, the formula gives you what the pitcher's ERA should be -- if variations in defense didn't matter. It uses only home runs allowed, walks, strikeouts and innings pitched. (Through the magic of Excel, I was able to quickly figure it, though my table-making Blogger skill is lacking.)
If you decide to swear by FIP, you'll see here that Matt Bush's ERA is more than double what it should be and that Nick Barnese and Paul Phillips are living charmed lives. These are through Monday, and I left Chad Thall in.
So, what say you?
UPDATE: I can't get this to line up to save my life. I surrender. Apologies.