My ds6-almost-7 is the same way -- he's in bed by 8 every night, but would stay up till 10 or 11 if he had his way!
He's in his bed at 8, we read a story together, and then we allow him to read quietly until 9:15 or 9:30. Then lights off. Sometimes he's asleep in 10 minutes, sometimes he's up another hour.
I don't have a problem with the reading -- actually, I read every night before I go to sleep. I just can't get into the sleepy mood without a good 20-30 minutes of reading! I often fall asleep while reading, and that suits me just fine. I need something to lull my brain, and reading familiar books does that for me.
We do make him turn the lights off, though, and I think 9:30 is pretty darn reasonable -- it's at least a compromise. He does still have 30 minutes of reading time and usually an hour or two nap on the weekends -- he turns into a whiny wreck around 5pm on the weekends if he doesn't nap. Odd, because he's fine on the weekdays ...
