Please, lets not get into a "yes it is"/"no it isn't" argument here!
I am aware of some rather horrid languages that forced the use of meaningful indentation, but that doesn't make indentation evil in and of itself.
As for in Lisp, a number of people have tried to add it to Arc (including pg) without too much success. It seems that meaningful indentation lends itself much better to statement based languages than expression based ones.
