Software is not a mathematical equation, nor is it a mathematical language. How anyone who writes software or professes to understand software could argue to the contrary is beyond me. Do people who write software actually think they are sitting down and writing mathematical equations and stringing them together? It is absurd to have such a narrow view of software.
The good news is that I do not intend to rebut this (and the rest of the post) here, because the comments to it, and those on Groklaw discussing it, are so good, and so varied, that it would be superfluous. If you ever come across people who have doubts about the non-patentablility of software, just point them towards those comments.