I ran into a similar problem with my DS. Had no idea what to expect from kindergarten, but I wanted him to be prepared. So we spent maybe 15 minutes a day working on letters and numbers. He had a fantastic kindergarten teacher who was so adept at teaching to each student's abilities, I didn't realize he was ahead of the rest of the class. Now he's in first grade, and while I like his teacher, she's just not as experienced as the one he had last year. It's November, and he has yet to do ANYTHING in school that he didn't learn last year. I have pretty much resigned myself to the fact that school (at least for this year) is just allowing him to socialize and learn to interact with other kids, and we've been supplementing at home.
Anyway, my point is that if your child is ahead of the class in Kindergarten, don't panic. You still have options. Most schools have a gifted program (which, in my son's case, is 40 minutes a week - so he is bored for the ENTIRE rest of the week). Some will allow you to skip to the next grade. You can supplement at home. And if all else fails, you can always consider private schools or homeschooling. Good luck!