Let me tell you a story.
Once upon a time, there was a girl. She met lovely boys from Chicago, Indianapolis, Boston, and a small town north of Dayton. She made it a point to tell these lovely boys, "I'm not your girlfriend. You're not going to tie me down when you live that far away. I'm not all that interested in uprooting my life for you, and I don't expect you to do that for me; sure, you're cool, but we're never going to be anything serious."
And so it went. Anything over an hour away was a dealbreaker, and she was perfectly okay with that.
And then one day, she was reading through posts on TFP, much like she did every day. She replied to one, much like she did every day, but this time she decided to check the profile of the person to whom she was replying. He, apparently, did the same, and they started responding to each other in threads, and chatting every day, which led to texting and phone calls.
To make a fairly long story a little bit shorter, she fell for someone who lived eight hours away. Something clicked with this one, and while the time apart really sucks, it will be worth it in the end.
***
So, yeah. Before, I would've said getting involved with someone long distance was pointless. I'm not saying that now
Certain things help, though, like settie said. There has to be trust. There has to be open communication. And really, the distance can't be permanent. There should be a plan, somewhere along the way, to remove the "long distance" part from the "relationship" part.