Yep-- haven't played with it yet myself, but it works just the same as launch control... settings are on the same menu. Probably best to use a clutch mounted switch for this.
The stock clutch switch actually works great with launch control... IF you're drag racing, which is also where flat shift would be handy. If you're driving on the street, or road course, etc, the stock clutch switch engages way too far out and it a real pain like Ben mentioned-- as you press the clutch in it enables launch control and limits your RPM, then you shift, and as you get back in the throttle and start to let the clutch out the launch control is still engaged because the switch is at the 'clutch fully disengaged' point. So you have a moment of hesitation while you continue to let the clutch out before you can rev on up. Sucks in such situations.
On a drag strip you'd generally be off the clutch so fast that this wouldn't be an issue, I bet you'd like the stock clutch switch actually.
Just did a bit more reading on flat shift in MegaTune (hit F1 from the settings page) and I need to test it but it looks like here's a way to STOP the annoying issue described above when using the stock clutch switch...
The flat shift settings are for use with a clutch switch and allow for different limits when changing gear. To disable, set the arming RPM above you maximum rpm If you press the clutch above the flat shift arming limit then the code uses the flat shift limits, else it uses the launch limits
So for example, set your launch speed at 2500, set flat shift at 6000, and as long as you hit the clutch (and it's switch) above that 2500 launch speed limit then launch control won't engage, instead flat shift will engage and will let you rev out to the flat shift limit (6000 in this example, whatever you set in reality). So this both works for flat shift, and should also get rid of the annoyance in between gears when using the stock clutch switch....
I gotta go try it once I get some sleep-- I've been up all night putting the new shopping cart in place, and it's 7am now.
MegaSquirt: So many features... so little time