Just picked up the latest copy of Auto Motor und Sport, which reviews the new Audi RS4. They have the following information about the new M3:
This fall the M3-free days will be over: The around DM100,000 ($50,000) sport version from the new 3 coupe will be launched. Conspicuous is the aggressive styling with powerful airdam and power dome on the hood. Underneath is a 3.3 liter (86.4 bore x 87 mm stroke) enlarged six cylinder, with at least 350 PS (345 bhp SAE Net - SAE is 1.4% lower than PS DIN) and 7,750/min redline.
The tires are staggered, 225/45 18 front and 255/ 40 18 rear. A lightweight version was rejected for comfort reasons. Also, a V8 variation using the 400 PS (395 bhp) M5 motor has been tried but is not coming for the time being.
Possibly a M3 Touring will come first.