Xander:
Reputation is purely for use in The Market Place section. It’s an ebay-like tracking system. So if you want to buy from someone, you send the money, and they don’t send you anything, you can give them negative reputation. Or, you can buy something from me, get exactly what you paid for, and give me a positive reputation.
This is all more clealry explained in the Market Place sticky.
Also, the Calendar abuse has been fixed, apparently the default settings allow unregistered people to post events in the Calendar… go figure. Thanks go out to those who helped us quickly put a stop to this! Ahh, the power of active administration!