The current reining Defcon CTF Champions, European Nopsledders posted their writeup for Bipolar, one of the two Crypto challenges worth 250 points.
AndrewL, author of many of the Crypto challenges from GitS in the past (and one of the former moderators of crackmes.de) has posted a great writeup of blocky.
Leetmore has the best selection of writeups, covering 8 different challenges.
Eindbazen wroteup Khazâd, and so did Georg, though his writeup counts for more since he solved it during the game hours!
Also, thanks to Eindbazen for making a pretty graph of the scoreboard! If you'd like to make your own graph, the final points and submissions by teams are online.