Soggy Balls at Coors?

On Tuesday, Brewers infielder Jeff Cirillo complained that the Rockies were using illegal waterlogged balls at Coors Field:
"It's pretty dramatic, wouldn't you say? Most shutouts in Coors Field, in the National League, when you take into account Petco, Dodger Stadium, where Washington plays. Those are huge parks." The Rockies have been storing balls in a humidor since 2002, but reportedly began leaving them in much longer this season. It's hard to argue with Cirillo after looking at the evidence. Here is a chart of Runs, Homers, and Hits allowed at Coors, along with rank:

          Runs   Rk     HR   Rk     Hits   Rk
2001      1458    2   1457    2     1270    4
2002      1440    1   1600    1     1232    3
2003      1243    4   1369    2     1146    2
2004      1412    1   1235    4     1240    1
2005      1285    1   1119    8     1254    1
2006       973   17   1114    9     1021   11

Pretty amazing. Joe Sheehan looked deeper at the evidence and produced this chart:

          XBH/CT  HR/CT  XBH/FB  HR/FB  BABIP
2001      1      1       1      1      1
2002      1      2       1      1      1
2003      1      2       1      1      1
2004      1      5       1      1      1
2005      4      9       3      7      1
2006      14     15      8      13     10

XBH/CT: extra-base hits per ball contacted
HR/CT: home runs per ball contacted
XBH/FB: extra-base hits per flyball
HR/FB: home runs per flyball
BABIP: batting average on balls in play

These are drastic effects. The Rockies have completely changed the way the game is played at Coors, turning a hitters park into a pitchers park by messing with the balls. How is this acceptable to MLB? And can other clubs do it if they want their pitchers to have better numbers?