The current BMW E90 generation is soon coming to an end, including the E90 M3 sedan. Based on the official BMW production schedule (see below), all E90 3-series and E90 M3 sedan production will cease in October 2011
M3 coupe and convertible fans have some more time, however. The E92 M3 and E93 M3 will continue to be produced until at least June 2012
(along with the 3-series coupe and convertible). Whether they will be produced beyond June 2012 as 2013 model years is not yet known.
Moral of the story? Anyone interested in securing perhaps the last naturally aspirated M3 sedans, should place your orders in ASAP.