Maybe I've got the regulator hooked up incorrectly?

Actually, in looking at the pinout on the package (which is a terrible diagram by the way) I think I may have done just that...

(edit)
Yeah that was it.

But still the highest voltage out I can get with the pot at its limit is 4.9. I can decrease it to 0V by adjusting it down, but it wont go any higher.
Wrong pot?

Change the multimeter to resistance mode again. Measure the resistance between Vout (middle leg) and Ground. It should be ~490ohms.

And this test produces the same ohms as checking the resistance between the pot legs.
??