There are two basic rules to constructing a good lineup.
1) Better hitters bat higher in the order. This doesn't generally matter for the pitcher slot because of pinch hitting. Batting the pitcher 8th instead of 9th probably increases their PA by like 5-10 at most. Most slots it is by 30.
2) High OBP guys in front of high SLG guys. Batting the pitcher 8th here allows you to slot a high OBP guy 9th which is in front of higher SLG guys at the top of the order.
If you were to design the perfect lineup for the Brewers you would probably have Fielder batting 2nd or maybe 3rd, certainly not 4th where he actually bats because it wastes his OBP. You would have Braun batting 4th or 5th where his lower OBP doesn't hurt you but the high SLG helps you. Kendall would bat 9th and the pitcher would bat 8th.
There is a guy who has tracked every single AB with Kendall 9th so far this year in the game threads at http://blogs.jsonline.com/brewers/default.aspx
. He simply rates each AB as good that Kendall batted 9th, bad that he batted 9th or indifferent, So far the net result is +6 in favor of the good that he batted 9th.