They are writing it during this weekend, but press release for hackathon was month ago (http://pastebin.com/sKKnRL19) and if I recall correctly he was hinting something about this project month or two before that. So there has been time for planning.
And like Tuna-Fish said, Finnish high school courses are quite limited and self-contained.
The scope (Finnish Lukio class maa1) is very limited, making this quite feasible.
No, it should be something which is written over decades, like the Linux kernal.
But a good open-source core will be a nice starting point.