This is meant to be an honest reply to you, Jewboy -- if you would leave your personal feelings against Leibowitz aside for a minute or so. The problem of "Kabbala as a tool" (even intented for the highest possible goal: to serve G-d) is that by definition, a tool is designed to serve us -- first. (I put it in a slightly different way in my first post.) Now this point is not so innocuous as it may seem -- as HaRambam defines it as idolatry in his Mishneh Torah (Hilkhoth Avodei Kokhavim). The Vilna Gaon is, some respects, even stricter than the Rambam, since he forbids mentioning anything about G-d, even His existence. This is something basically aporetic and intimidating in Leibowitz' formulation of the Rambam's ideas, I admit. One is tempted to ask "but if this is so [if any tool that we develop, be it kabbala, philosophy, etc, is per force idolatry], where do we get from there ?" The point is that we do not 'go anywhere' but 'stand before G-d'.
No change in medical status among Jerusalem Gay Pride stabbing victims (Haaretz)
from the article: 'Prof. Leibowitz, does man have a soul?'