I actually ended up at Kachina hummer in Phoenix AZ over christmas, and asked them to check for any computer/pcm updates. They did, and said there was nothing to update (as far as the service sheet showed...but I know they fixed the airsuspension). Later, someone posted this link:

http://calid.gm.com/vci/VINEntryPre.do

just enter your vin number, and it'll tell you what updates you've received for your vehicle. Mine matched everything listed above by Paragon. I'd check before approaching the dealer...just may save you some time...

After reading this thread, I rushed my rig to the dealership since my warranty is about to expire. Along with all the updates Paragon stated above, I also had them flush my tranny. Mine is a '03 with only 17k miles on it Anyways, the result is definitely noticeable as far as the shifting point. It's now upshifting @ higher rpm, downshifting quicker, and smoother shifting all across. I don't know if it was the reprogramming or the flush but no doubt it drives much better now

The only downside is instead of an increase in mpg, i've noticed a decrease so far I'll do some more driving to confirm this but regardless, it feels like a brand new truck

Went in for the recall, immediately my mileage doubled & the acceleration was noticeably better from that instant. I was amazed. Alas, it didn't last. As soon as I returned the SRX loaner & picked up the H2 all returned to normal, 12.5ish mpg & rather ordinary acceleration. BooHoo.