Gnota is the gradebook client I mentored Leandro Lameiro on for last year's Google Summer of Code. We used Python and GTK in part to ensure easy portability to Sugar. Getting it running on my XO was pretty easy, just
sudo yum install python-elixir bzr python-nose, and all you really need is Elixir to just run the code. You can get the source from Launchpad and fire it up. It looks pretty good:
I guess there is a Sugar GTK theme that makes GTK apps look Sugar-esque even if they aren't fully Sugarized.
But half of the tests fail and the responsiveness is horrible (like, click a cell and get a cursor 5 seconds later). I suspect the failing tests (and a good chunk of the performance problem) comes from Fedora using a different version of Elixir and SQLAlchemy than Leandro used. As the serious-minded mentor, I should have forbade the use of those still rapidly evolving libraries, but I couldn't resist the shiny either.
Jennifer really wants a gradebook for her XO (and I'm sure she's not the only one) and she can't connect over the school's network to use a web-based tool, so I'm going to have to take half a crack at making this usable.