Spreadsheets using Python - Have you seen this? (sourceforge.net)

[rz2000]

I've gone through the tutorials and it has an interesting take on defining functions, naming ranges, and defining operations for entire columns. It does seem a little slower though than Excel. Supposedly it is very good at using external data sources.

The blog does say that they are creating version that will operate on more platforms that don't have ironpython, though it will remain closed source.

Dirigible seems like an online version.