Racket makes it easy to fire up a Scheme and start doing work. It's the flexible, usable lisp with libraries that I was waiting for. There's less cause to drop SICP from the curriculum when you can get a high-quality scheme distribution and tooling on several platforms :)

They should improve out-of-box usability. You shouldn't need to pick a language when you first install it - that's a barrier to new users. Have a default (the shapes one described in the getting started area would be fine), and make it easy to change.