Here's an interesting article from Teltarif, a German telecoms website about the extension of mobile network coverage in the Munich tube. According to the article, the cost of 20 base stations and 125 antennas to cover additional 80km of tunnels and 20 underground stations was shared between the four network operators of the country. One of them, Vodafone, was the technical lead to get the extension up and running. It's not mentioned whether it's 2G only coverage or whether 3G coverage has been added as well. Can anyone from Munich comment?
The article ends with the note that previously, polls have always indicated that a majority of passengers was against mobile network coverage in the tube. Lately, however, that has changed significantly, perhaps, as the article speculates, due to the rise of Internet use on mobile devices.