Great stuff. I think the author may be using the release version 0.2, as the boot time issue has been rectified now for the most part in the next release, 0.3. The next big slow-load issues is packages, that'll be post 0.3 though.
I have still not taken a serious plunge with Julia, testing waters.
Any plans for doing the same to individual scripts ? It would be handy to start off from the last known set of JIT'ed functions, may be retiring paths that are no longer frequented.
There is a mechanism for including package/user code in the system image if you compile Julia yourself. It works well with a wide range of packages, but the goal is to generalize this and make it usable with binary releases, and probably to compile packages to separate shared libraries.
(Aside from that I really love the language, and I'm looking forward to doing more with it.)