Since it came up, here's some more info (law was adjusted in 2004).
1) If you're in a state employee job, you're exempt from paying Social Security (at the very least, for elected officials).
2) When you retire, your Social Security benefit will be reduced (bottom of that PDF file, Page 42, although it only gives an amount of reduction for spouses).
3) State employees are exempt from paying Social Security, so their benefits are reduced by the wind-fall elimination program. That page gives links to charts and workbooks.
4) Here's an STRS page on it.
5) The OPERS site is less than helpful on this matter.
Keep in mind that this only covers people who have paid into both the Social Security program long enough to be vested (full benefits after 40 continuous quarters or 10 years) and also work in a job that exempts you from paying SS and provides another pension benefit (ie. you've worked various jobs, or are currently working 2 or more jobs, one of which is a federal, state or local government job). The time you're working in the OPERS or STRS job, you're not having Social Security withheld (so those quarters don't count - at least for the pay you get from that job if you have 2 or more jobs).
As always, it's best to consult with your financial planner, or the retirement coordinator at your place of employment.
Hope that helps.