I think the most important take-away for me was how important careful planning is right at the start. As we got closer and closer to the deadline, the code got nastier and nastier. But I made sure we spent several hours just planning our design before even touching any code, and that the foundation was solid. It wasn't until the final 6 hours or so that we had other entities animating on the screen. But by then everything just came together, and filling the game with more content and additional levels was a breeze. Need to add a complex feature? Great! We've already planned for it, and it takes 2 lines of code.
There's a short little blog entry I read years and years ago that I still remember, called "Black Triangles" which is similar. About developing a game for the original Playstation, and spending over a month to just get a black triangle rendering on screen. http://rampantgames.com/blog/?p=7745
We actually have decided to take our little game past the weekend, so maybe this will become our first One-Game-A-Month Game.