On Monday 2007-04-02, 08:00 UTC (10:00 CEST, 01:00 PDT), we'll be switching over the source repository machine to use a slightly different environment for repository access, which should hopefully fix the hangs some people have seen.
There should be hardly any downtime, but you're nonetheless advised to not do any SVN or Mercurial operations around that time. If there is any outage, it will not be beyond 09:00 UTC (one hour later). - Frank