The upcoming script.aculo.us stuff is being implemented in Backpack, and will soon be in Basecamp. You can see a video on the 37Signals blog.
Thomas Fuchs is single-handedly revamping the web experience. While it's the packaging with Rails that will bring it to the wider community, Thomas' work will soon be the benchmark for providing that shiny Web 2.0 experience in a clean and convincing manner.