Just wanted to give a heads up to my fellow travelers. On Saturday I was planning on taking the S-8 line from Marienplatz to the airport. Arriving at the station I found out the S trains were not stopping that weekend at the station. I don't know if this is every weekend or just my lucky weekend, but they are doing a lot of construction in the station. There was nothing on the http://www.mvv-muenchen.de/en/homepage/index.html website mentioning this, nor is there anything posted now.
The Bahn website shows the same situation for next Saturday as well, and for Sunday, but not for Friday. They show taking the U-3 to Moosach and the S1 from there to the airport or two U-Bahn to Ostbahnhof and the S8 from there. MVV does talk about it here. It is apparently due to preparations for work on the S-Bahn tunnel under town.