I'm curious to know whether ArcGIS Desktop 10.0 will support newer versions of Python than 2.6. And for that matter newer versions of NumPy (ie, 1.4, 1.5 etc). I'm sure that this documentation is on the ESRI site somewhere, but I can't find it.
I have found that ArcGIS Desktop 10.0 will respect an existing Python 2.6 install as long as you have Numpy 1.3.0 installed (ref), and I'm guessing, at least until Numpy 1.5.0 is out and supporting Python 3, then no Python 3 for ArcGIS, but I'd still be interested to know if upgrading is possible when it's available.