For god's sake, why?!?
Shimano LX is no longer (yes, I know, many of you geeks knew this months ago) being produced, as of the 2009 model year, at least not for mountain bikes. Now it's a "trekking" grouppo. It has been "replaced" by a group called "SLX" which is oriented towards people who throw themselves off of things on bikes (note that I have nothing against these people and in fact am one of them at times) and looks as if it was designed by someone who watched X-men 2 a few too many times.
Here's the thing - SLX is 25% (give or take a few bucks) more expensive and 10% heavier (at least if the always-dubious claims can be believed) than the old LX group, which was really no slouch in the strength department. Shimano says the SLX crank, for example, is *twice* as strong as XT. Really!
The serious hucking crowd runs either Saint/high end tomfoolery, or old STX-RC parts they found in a bin in their parents' garage. We don't need another kinda-heavy, kinda-beefy "midrange" group - and I really think an inexpensive XC-oriented mountain bike group is a good thing to have in the lineup. XT is expensive, for crying out loud!
Also, I miss the old LX crankset - which was identical to the XT crank, but half the price, with steel chainring bolts rather than aluminum being the main difference. $5 worth of chainring bolts later, you had an XT crank! Sweet! Fortunately, the LX technology (ie, hollow crankarm, integrated spindle and external BB) has made it down to the Deore level now - so that's probably what I'll be rocking (or running) when my current LX cranks die. I hear they're godawful heavy, though.