My son stopped napping when he was two, but closing in on three years old. It coincided with weaning him from the pacifier. He just wouldn't fall asleep without it during the day; although at night, I guess he was much more tired, and didn't have any trouble without it. He would occasionally fall asleep in the car when I went to pick up my older child from school, so I guess he wasn't totally finished needing naps at that point.
As long as your child is getting plenty of sleep and isn't tired and cranky, then I think he's fine whether he naps or not. My daughter loved to nap but got to the point that she was four years old and wanted to nap from 4:00-6:00 p.m. -- then would be up all night! I had to break her of her nap habit at that point and it wasn't pretty. Dinner time was pretty bad for a couple of months because she was so cranky during that time, but letting her sleep that late in the day kept her up too late every night. At least your son is putting himself on a normal family schedule.
I think if he is happy and doing well you have no worries. If he begins having behavior issues or is always crying and cranky, you might want to try to reintroduce nap time. On the other hand, I guess there's no such thing as a two-year-old without behavior issues, LOL.