I got the Scangauge II in the mail yesterday evening, and I installed it that night. I need to post a picture of the install, it's pretty slick.
Coolest thing is that it shows boost right out of the box. It measueres manifold pressure, in PSI(a). At full boost, it was showing 25 psi(a), which is 10 lbs. of boost. Sweet!
It also shows if you're in closed loop or open loop. Even half throttle gets you into open loop. Not a good thing if you're using a lot of ethanol!
It can show a number of other parameters right out of the box: ignition advance, water temp, intake temp, voltage, fuel consumption, fuel pressure, etc.
Fuel trim is not available out of the box. It needs to be added manually. I need to go over to the website and figure out how to do it.
All in all, it's a VERY slick package. Just having boost is worth the price of admission.