So far I don't have any gifted kids, just difficult ones BUT my cousin was/is gifted.

He never really attended school because they weren't teaching him the stuff he needed to be taught... eg - he was doing year 7 maths at 7 years old.
The only school my aunt tried though, was a private school (TAS in Armidale). She pulled him out after about 3 months & home schooled him for the rest of his schooling years (which she did the wrong way!)
He was on the front page of the Sunday Telegraph as one of the highest IQ's on Aust at about 10 I think.

He was also ADHD. The biggest thing for him was boredom. The need for constant stimulation & needing to be challenged... pulling apart old computers etc & putting them back together was a fave past time through his early teen years.

I can't tell you about services though... he was never lucky enough to have recieved outside help. His mother is a bit odd