Hey Jon,
I'm not sure whether it uses compression natively, but you could always pipe your dump into gzip on the remote end and ungzip the resulting string when it gets to you. I've never tried this before, so there might be some kind of encoding problems that give you issues. In that case (and if the data was particularly compressible) you might want to try piping the gzipped stream into base64 for the transit, though that would take more space than ideal (you might still get some bandwidth savings depending on your data).