I had looked into it a little bit, and it's pretty much like DMD says. You must buy property, pay taxes, and show that you are commited to staying in pennsylvania area beyond your four years of tooth school. That's why being married helps- they assume if you lay down roots with a wife and kids then you are more likely to stay. Also, you have to do this for a full year before you can apply for it, so you wouldn't get the state tuition till at least year 2.
HOWEVER, as per the people I discussed it with (including Brian), doing these things does not guarantee that they will grant you residency. You can reapply (yearly I think), and they may not give it to you one year, and then give it to you the next fairly arbitrarily. Which sucks of course, cause then you could have bought a house, have debt from that, and then not even save on tuition.
From the students I talked to at the school the only ones that were successful were the ones who were married. I got the general impression if you weren't, then it would be tough. If you ask Brian he can give you the emails of students who were successful at doing this, and they can tell you more about the process and clear up anything else about it. Good luck to ya, and enjoy Philly if that's where you end up- it's a great town.
