Travis Oliphant announced this morning at the SciPy 2010 conference that Microsoft is partnering with Enthought to produce a version of NumPy and SciPy for .NET. NumPy and SciPy are Python libraries for scientific computing. Oliphant is the president of Enthought and the original developer of NumPy.
It is possible to call NumPy and SciPy from IronPython now by using IronClad. However, going through IronClad can be inefficient. The new libraries will enable efficient access to NumPy and SciPy from .NET languages and in particular from IronPython.
Here is the official press release from Enthought. [Update: press release no longer available.]