Theory:

Launching at the drag strip (or anywhere where a good launch is required) is a delicate art.  The AWD can be difficult to master - we get so much traction in our cars that launching involves a lot more than "raise throttle, dump clutch".  Start from too low of an rpm, and you'll get shoddy acceleration and high turbo lag.  Start from too high of an rpm, and it will be difficult to prevent clutch spin.  Let the clutch out too slowly, and you'll superheat the clutch face and get clutch spin all the way through first gear (and maybe second, and maybe even third if you *really* screwed it up).  Let the clutch out too quickly, and you'll bog (rpms drop) due to all of the traction from the AWD, leading to the same poor acceleration and turbo lag as if you had launched from a low rpm.  The exact rate of each (clutch out, throttle in) is what requires mastery - your goal is to get the clutch and flywheel locked up as quickly as possible *without* letting the rpms fall whatsoever.

At the Strip:

When rolling up to the line, use the clutch decisively.  Babying it will heat it up prematurely.  Pull into the staging beams and, keeping the transmission in neutral with the clutch out, sharply race the motor to 4000 RPMs a half dozen times.  By this point, your rival is beginning to stage.  Put the transmission in gear and slowly tach up to 4800 RPM (5500 if using an RPS clutch).  Concentrate on holding the RPMs steady.  When the lights come down the tree, slip the clutch on the last yellow light.  Quickly apply more throttle, increasing RPMs and easing the clutch out the rest of the way.  The accelerator should be on the floor at the same instant the clutch is fully out.  You should be at full throttle at the 60' mark.  Don't worry about red-lighting - you didn't.  Just be prepared to shift into 2nd gear, since you'll be accelerating so hard you'll reach 7000 RPMs (42 MPH) in just over 2 seconds.  A hard launch will generate enough G-forces to pull the parking brake back, causing a red light to flicker on the dashboard.  At 6800 RPMs, stomp the clutch all the way in, and, while lifting to 1/3 throttle and bang 2nd gear.  Let the clutch snap out.  A good shift into second should feel like the rear bumper is coming off.  Forget your bumper and mash the throttle back to the floor.  If you got this far without smoking the clutch or grinding 2nd, you're in for a hell of a ride.

On the Street:

On the street, all-wheel-drive rules.  The technique used at the strip is overkill since your opponent won't have traction off the line.  Instead, rev the motor up to 2000 RPMs while the light is still red.  When the light changes, quickly bring the motor up to 3500 RPMs and slip the clutch.  Roll out smoothly for no more than 1 second and floor it.  You won't have the velocity of a hard launch at the track, but there's still nothing on the road that'll beat you from zero to sixty.

Caveat:

There is another camp of folks on this list who believe that a better way to launch is to tach up to a higher rpm (5000-6000), and dump the clutch as quickly as possible.  This other method relies on the hope that the drivetrain will lock up instantaneously, causing the slack to be taken up by tirespin instead of clutch spin.  I believe that this method creates shock-loading of the transaxle and transfer case and can lead to premature failure of either or both, but that's just my opinion.  Basically, the "slack" has to be taken up somewhere.  I believe that the method I use causes the clutch to absorb all of the slack, and causes no shock-loading to any of the gearing (transaxle, transfer case, driveshaft, differentials).