not saying that this difference in salary is right at ALL, but did you negotiate your salary when you were hired? he might have taken a more aggressive approach in negotiations. granted, they probably offered him more to begin with because there's no way that he asked and won $20k more in negotiations.
Sometimes if people have a higher degree they'll pay them more and it's 'justified' but if he has the same education as you there really isn't an excuse. I would talk to your boss and tell him you want more money, explain why and try to keep your co-worker's salary info out of it... but if there really isn't any reason (education etc) they are paying you less then they are technically violating the Equal Pay Act (an ammendment to the FLSA) so even if he did negotiate a higher salary they should have upped yours as well. So many places do this though because what are the odds of people actually finding out what their co-workers salaries are?
