In case anyone is interested, here are the carpet cleaner recommendations that I received from several neighbors. I've used asterisks to indicate the number of referrals for each company:

***North Side Carpet Cleaning - (412) 344-3740 
*Kemper Carpets (412) 835-2202
*Yacko's Cleaning - (724) 335.0876
*Perfect Carpet Cleaning, Inc. - (412) 567-0203
**COIT - (412) 241-1880
*Doug Weiss - Fiber-Seal  - (412) 262-2108


Thanks!
Jessica