I have heard differently. I did some reasearch on German internet pages, and found that just about everybody says it will be offered in both SMG and Manual. However, none of the sites were official from BMW, so I can't guarantee it
I am personally not worried because I am going for the SMG, but I hope they will offer it in 6-speed just because I want my fellow M3 Passionates to have the option. I think it's fair to say that the M3 is more of a driver's car in comparison to M5 and M6, therefore I really hope BMW will offer manual.