I saw half of Led Zeppelin last weekend....just not performing together.
Plant was onstage with Buddy Miller and John Paul Jones was onstage with Giant Sand at a music festival I attended.
Plant's been doing the folk concert circuit for awhile now. I heard him interviewed a few years ago regarding some current projects... he said some mildly controversial things about traditional southern folk music he was experimenting with.
It may have been a reaction to criticism LZ got for borrowing delta blues riffs early in their career.