Depending on the kid's level and unique needs, I think one might find out that one runs out of local school resources extremely quickly. For DS13, we wasted a lot of time trying to work things out at school (we had false hope). The teachers kept telling me that he did receive enrichment, but his impression was that even the enrichment was incredibly easy. By 4th grade I systematically taught him at home (afterschooling). By 6th grade, there was finally some formal acceleration at school but it was pretty useless. By 7th grade we completely gave up hope and used school simply as a social place.
Community resources could be great. We did find lots of opportunities at the local university. But most of the community resources outside of the university are also not geared toward GT kids, and we find our kids maxing out at most places pretty quickly. My DD9, for example, has nowhere to go anymore in the local community for some of her very strong pursuits.
Online school is great (Art of Problem Solving) for DS. Afterschooling remains the main learning approach for both kids.
I think the key is for the parents to prepare early (we really weren't prepared for DS which contributed to his misery at school for a few years), and use outside-of-school resources.
