From what I've read, the LCI in the 2010 M3 will have new LED tail lights only. That's the only upgrade. There is some speculation as to whether or not this LCI is making it a 2011 or what some would call a 2010.5 model. No one seems to know for sure. My dealer in Germany told me that if I put my deposit in April like I plan to, it will be a 2011 model and not a 2010. That's all I have to go on though...
The 2011 will not have a new engine from what I've read here.
'11 BMW E92 ///M3 - ZCP and DCT
'13 Toyota Tundra - 4x4 Platinum CrewMax, 5.7l iForce V8