I was shocked last week when we have been shown in "Mathematical Optimation Technics" that they do their stuff with Excel that it is extremely powerfull when it comes to any kind of math but this is definitely another very interesting usage of it :)
I know someone that came up with a similar idea about 6 years ago. He started an AI system and showed it around GDC around 2001. Unfortunately the team split up a few months later after funding fell through.
AI in Excel, wow that's novel! "The spreadsheet that can think!"