I'm picking up my new 07 truck w/the 5. 9 next week.

In checking the build sheet on this truck, it apparently left Fenton MO around the 1st of December 06. Its only got 100 miles on it now -so mostly being moved around on the dealers lot & maybe a demo ride or 2.
I plan on immediately changing the oil, & the oil/fuel filters. Since the truck has spent a long time sitting, would you be suspicious of any other items ?
I wouldn't worry about the time it's been sitting, at least not the oil. Two things I would check are the batteries and shocks. Hopefully the dealer makes/made some effort to maintain batteries... good thing to check right where it sits/sat, before they prep'd it for final sale. Only reason I mention shocks, if it didn't roll around at all for 8-9 months, they might leak early. Not a big deal but gives you a little leverage if they become suspect before the warranty ends. Most of the things I'd want to check will be fixed or hidden when the dealer prep's it for you. Next time, take a multimeter, camera, and tire pressure gauge... use before they prep... good leverage for warranty.
Go over all of the seals, gaskets, etc around the windows and doors. They are much easier to fix early before the sun, dirt, and time make them "set up".
Since it's probably been sitting with about 1/8 tank of fuel, I'd get a water seperating additve in there and fill it up IMMEDIATELY. Good time for a little overkill (and inspection) with the drain. Water (IMHO) is probably one of the things hurting CR injectors. Stay ahead of it.
Ask them to verify it has the 7u (vs the original 10u) fuel filter in it. The revision might have preceeded your production date and I don't know if they used a Recall or TSB. If they can't find out, maybe ask them if they'd just change it out w/1st oil change...
Can't hurt anything getting the first oil change in early but... I'd wait until at least 500-1500 then use your "1st free" change at the dealer. Then start using your own schedule, oil, and filter (of choice) as if you still had the factory oil. That'll give the first filter "you" choose a head start at removing break in/assembly "stuff".
Better to spend the time and $'s on fuel to drive around "easy", enjoy the new truck, and actually follow the "break in" advice in the manual. Carry a notebook and WRITE DOWN every little gripe that comes to mind... everything. 1st trip to dealer for "free" oil change, go over the list with service. If you use the notebook to stay concise and focused, a good service writer will talk about just about anything... and fix a lot of "little" things they might resist later at 20-30K. Good chance for you start a positive relationship, whether you plan on using them for maint. or not. No matter how much you like or hate dealers, nothing beats having a good contact in the service department where you bought the truck. Good chance to check some prices at the parts counter too... maybe buy a spare fuel filter or something. Nice to have them remember you too. You'll need them sooner or later.
You're smart buying now... last chance for a 5. 9 and getting max discounts. 6. 7's are going to be a royal PIA for those of us that try to do as much of our own work as possible. Good choice.
Congrats...