In general most places play with either current or old rules but unless it is a USAV event, it's a good idea to find out what the house rules are.
I know when I play outdoor tournaments every where has their own rules. Some variations are:
- Height of ball that guys can touch in front on 10' in R-Coed
- Touching Guy Lines
- "Clean" hand sets
- Scoring
- Let Serves
- Block +2/ Block doesn't count
- Kick Serves