- interactive sliders to manipulate input parameters
- support for inline plots (like IJulia)
- very nice code completion
For example, the pretty picture in the header of the Juno page is also a Julia project. Yuri Vishnevsky gave a lightning talk about his graphics demo at the same meetup last night. See  and  for more about that.
Beyond the main LightTable presentation and the generative art you mentioned, there were also lightning talks on:
- calling JITed C++ from the Julia REPL with Clang .
- spectrograms, audio playback, and tone generation with interactive manipulation from IJulia .
- Kalman filters 
This is really impressive.
It also offers a level of exploration (with the in-place results), which is a neat thing for students – I've found that interactive environments generate interesting solutions to otherwise boring problems. I'm currently trying to replace Matlab as the language I use in our university's Probability class and Juno adds to "why use Julia" argument :)
There have been numerous articles linked to HN about Julia, I suggest you check in more ;)
This looks really cool, I've played with Julia a bit, but a Light Table introduction might be just the thing to make me dive deeper into Julia and start trying out Light Table a bit.
Still waiting for PyPy to eventually replace CPython as the reference implementation. Even though they still have a bit of catching up to do.
This is what I get on Linux 64bit and Julia git build when I press Ctrl-Enter to evaluate the line.
INFO: Couldn't find Jewel package, attempting installation...
We couldn't install Jewel.jl for you.
Try using Pkg.add("Jewel") in a Julia repl.
Edit: This http://junolab.org/docs/notes.md also returns a 404.
That should be notes.html, I'll go ahead and fix that.
See  for to Yuri's code for this (I actually used my own, but his is way better).
exp = :(a + b * c + 1)
--> exp. shows head, args, and typ
--> typeof(exp.) no suggestions.
me = Person("", "")
--> me. not working
--> println(me.) not working
Cannot submit issue on Github.
At the same time, R's ecosystem is huge and a lot more mature than Julia's, so for the average user who just wants to pull in data and plot it, etc., it's a far better choice.
Julia is more like Python or Ruby, and not quite as data-oriented as R, but feels a little more like a general purpose language...