Not exactly. They did a show called "Rescue From Gilligans Island" in the late 70's where everyone was picked up and taken off the island. The show chronicled the difficulty they had reintegrating into society, and at the end a plot by a Soviet agent landed them back on the island again.
A couple of years later a second TV movie was made ("Gilligans Island Castaways" if I remember right) in which the people were finally rescued permanently. The Howells ended up buying the island and they all made a fortune after turning it into a resort.
The movies weren't very good, but they did wrap up the storyline. The actual final episode of the series wasn't a finale at all, and was written to be just another random episode. The movies were only made to bring some "closure" to the storyline.
It always drove me crazy that they could build all this wierd stuff but could never patch up that little hole in the boat.