Yup, keep upshifting until it lugs, then back off a gear.
Kidding - sort of!
You definitely want to be in the highest possible gear once you've finished accelerating. Downshift if you need power.
It's a major way manual transmission drivers can smash their cars' EPA ratings in urban driving. EG:
http://ecomodder.com/forum/showthrea...cra-30059.html