Since September 24th the DBB (U-bahns, tram, and bus services) have been striking in Bavaria. It's been most paralyzing here in Munich where visitors have had to find other means of navigating their way to Theresienwiese. Thankfully the strike was discontinued this morning for family day at the Wiesn. It's possible the strike will continue, although the MVG is hoping that doesn't happen until after Oktoberfest is over.
The most recent updates on closures and delays can be found on the MVG site.