Yes, Nacht and I are an example of where an internet romance became real life in every way. I know this isn't how it works for all such connections and I don't even know that it is 'common' for people who hook up this way to end up together on a permanent basis, but from my own personal experience, it is possible.
For the record, I met Nacht on another board, we talked by voice connection, icq and phone for several months and then we decided to meet in person to see if things might work out on a more permanent basis. About a year after we met, he moved out here and we are planning a wedding. So it worked out just fine by my reckoning.