How to invoke ipython in Mac OS X?

[Lou Pecora]

I installed the SciPy superpackage and have pylab, matplotlib, scipy, 
and numpy apparently running well.  But I want to use matplotlib/pylab 
interactively.  The instructions suggest doing this in IPython.  But 
using ipython on the command line gives me an error.  The system doesn't 
know the command.  Apparently there is no ipython executable in one of 
the bin directories.  I thought the superpackage would add that 
automatically, but I guess not.  

Can anyone tell me how to get ipython running on my MacOSX 10.4 system?

Thanks for any help.

(Yes, I asked on the SciPy email list, but never got an answer.)

-- Lou Pecora  (my views are my own) REMOVE THIS to email me.