it all boils down to how badly the two people involved want the relationship to work. i had a long distance relationship (i was in L.A., she was in the Philippines) for a year, having been together for two years prior to our separation. phone bills were horrendously high. the distance itself didn't destroy our relationship. we were having other issues altogether, and the distance just made them that much more difficult to resolve.
there's a very appropriate quote which applies (if i can recall it correctly) --> distance is to love what wind is to flame...it extinguishes the weak and it feeds the strong. (or something like that). if both people have a strong relationship to begin with, have some means to communicate regularly (whether by snail mail, email, instant messenger, etc), and some opportunity to visit each other in the course of the separation, there is a good chance it'll work out.