I would love to get a closer look at ironpython, however as far as I know it is currently an unreleased research prototype.
There was a lot of promise in the early .NET days. Seemed we were going to get a lot of languages:
APL
Forth
Perl
Python
Eiffel
Mondrian
Some ML language (F something?)
Haskell
X#
S# + 1 other Smalltalk
...
A lot of this is research prototypes and I get the feeling that launching and supporting an industrial strength language (that lasts) takes a lot of resources. Even MS gives fairly low resources to JScript.NET.
I'm not using but I guess that Eiffel and Dyalog APL have their followers. (X# is, I believe, being subsumed into the CLR.)