This may or may not be significant to you, but as I'm sure you know, the '09 M3 will come with the new iDrive. IMO, the iDrive is the weakest link on any BMW. The update should make it much easier to use, more useful, and provide additional features. The '08 M6 will have the old iDrive. No one buys BMW for the iDrive, but it's amazing how much a little every day useability plays into your enjoyment of the car.
2009 Interlagos Blue E92 M3 (Sold)
2004 Silver Gray 330Ci ZHP (Sold)