If you are interested in all the various things that Mapnik community members worked on during last week's sprint, then check out the wiki page summarizing blog posts and other items at the MCS01 Results page.
And keep an eye out on the mapnik-devel list over the next several weeks as additional things participants worked on come to light. Some projects started at the sprint are so cool they will take some time to mature. For example, Frederik Ramm started working on a new rendering backend to Mapnik that will output not maps, but rather statistics about how they were created. This will be invaluable for people running servers on Mapnik that want clues on how to improve the performance of their stylesheets. But writing a new renderer is a big task, even for someone as prolific and talented as Frederik, so stay tuned and I'm sure he'll report on his work soon.