One thing that's helped Rails adoption a lot is that you can get the whole thing up and running in 3 steps: install Ruby, install Gems, get Rails. All of this is available from one page on the Rails site, so it's really easy to try it out. You don't even need a web server; they provide one for you.
Lisp in a Box is the closest thing Lisp has to this, but can anyone seriously say that asking people to learn Lisp, Emacs and SLIME at the same time is the way to get people hooked on the language?
I think what Lisp actually needs is a nice, easy install package: Scheme/Lisp, a nice HTML help/tutorial system and a simple editor, like the one that comes with Ruby (basically Notepad with syntax highlighting and top-level integration <-- this is the key feature). Perhaps you could throw in some kind of web-app package that people can start playing with (just like the one in Arc) and a package system (one as easy to use as Gems would be nice). All of this should be wrapped up in a single installer.
This way, people have a nice, gentle introduction to the language through a simple but expedient system, and can graduate to Emacs/Vi/Eclipse at their leisure.
Oh, and big, colourful, idiot-proof websites with the instructions on them are a big draw too.
