If you haven't yet, you should check out a build of 1.0. The start-up time is _greatly_ improved. Basic startup time is twice as fast as ipython for me now:

$ time ipython -c '1+1' Out[1]: 2

real 0m0.493s user 0m0.401s sys 0m0.063s

$ time julia -e '1+1'

real 0m0.222s user 0m0.115s sys 0m0.101s

Yes, python itself is still much faster. I compare against ipython just because that used to be my go-to interactive shell for technical computing.