I really like the way you're simulating an actual development effort including the surrounding process (requirements, planning, design, refactoring, etc.) and, unlike most "academic" articles, creating a non-trivial system that ties several individual concepts into a more real-world whole.

This reminds me of the excellent ASP.NET 2.0 Website Programming - Problem, Design, Solution book, which uses a similar approach.

I look forward to reading (and even participating as a "team member") the rest of the series.