What is the difference between IronPython and BOO? Is there a need for 2 Python-like languages?
IronPython is designed to be a faithful implementation of Python on the .NET platform. Version 1 targets Python 2.4 for compatibility, and version 2 targets version 2.5 (although most of the Python standard library modules implemented in C aren't supported).
Boo's stated aim is to be a "wrist-friendly [dynamic] language for the CLI." It takes a lot of inspiration from Python, but diverges on four main points:
There are some other minor differences in implementation/performance, but the divergent design goals above should (IMO) inform your choice of languages.
Two more things to take into account are maturity and community. Python is much more mature than Boo, and has a much larger community. IronPython also has the explicit blessing of Microsoft.