Yes, I actually organised my grades 10 year reunion about 2 years ago. It was a really good night.
I thought that being most people still hung around the same groups since school plus minus a few different new friends, that there would be seperated groups, but there wasn't. We had around 250 people in our grade when finishing year 12 and i managed to get ahold of most of them with around 200 people turning up.
It was so good, I was very happy with the turn out, and it was great to see everyone. Most of us looked the same but the attitudes had matured and everyone was happy to catch up with each and every person.