Lifting satellites: space elevators or HARP guns?

There's an article at Slashdot about the LiftPort space elevator.
I think this sort of research is fascinating. While I'd be the first to admit I don't expect to see a space elevator in the next ten years (or probably even forty), it's driving some good research and I think will have value in other ways. Airships could be making a comeback, and the space elevator concept could be useful for lifting items up to them.

There's no mention in the Slashdot story of Project HARP. This is a fascinating research project to essentially fire satellite payloads into space using a very large gun.

This idea was driven by a controversial scientist (Gerald Bull) who was subsequently assassinated. Following this, the funding offered by the American and Canadian authorities was stopped.

While I think the LiftPort ideas are interesting, I believe the future of the high altitude gun is much more attainable.