What is your price range? Willing to live in the city?
If you're looking to live among young professionals, I would highly recommend living in downtown or midtown Harrisburg. If you don't want urban city but don't want suburban schlop, Camp Hill is a nice choice.
Harrisburg has plenty of apartments and townhouses for rent, from historic sublets to high-rise apartment buildings. Camp Hill has apartments as well, but it's going to be more expensive.
Here's craiglist's apartment listings:
harrisburg apts/housing for rent classifieds - craigslist