It has been reported that GSB repository is broken after some people reported that their local copy of the repository is now gone (or precisely deleted due to --delete parameter on rsync command) since the upstream repository was gone from the official repository server.
This problem was reported on LQ and also on the GSB mailing lists and the developer is now investigating this problem.
For temporary workaround, Ponce has a local copy of x86_64 version of GSB-3.2 for Slackware-13.37 that you can use (sorry, not 32 bit copy yet).
Once the problem has been resolved upstream, the mirror will likely to get the updates within 24 hours and you can start syncing again with your local copy.
Update (7 January 2012): 32 bit repositories are now back online on UKDW Repo server. Meanwhile, the 64 bit remains not available at this time. Please refer to Ponce's server until this problem has been solved