Yes, 2.6GHz is the IDA (Intel Dynamic Acceleration) frequency, but not guaranteed at that speed. 2.4GHz will be what's marketed from manufactures.I believe you're looking at the wrong number. 2.4GHz looks like the Merom max to me.
Yes, IDA is hardware based, but the core idling must also be handled by OS.You're reading it wrong. The T7700 is 2.4GHz clockspeed, and with IDA it can go up to 2.6 (I said 3.4 which I was wrong about).
Additionally, I believe that the IDA is mostly hardware based, so it doesn't need os x drivers to work. I could be wrong though.