Penryn QC mobile will come into existence soon.

Intel's reasoning is your processor won't be running at 100% all the time. If it is then the program you're running is either over-taxing your proc or is very poorly written. So they measure TDP as around 80% of the max (need to verify this).

TDP is not exactly a good way to measure heat generated by a proc. TDP is more of a yardstick for engineers to know how much heat can be safely dissipated by a cooling solution.

i.e. target TDP is 20W + other variables (junction temp etc)
Based on some formula they need to use certain heatsink material (alu or cu) and certain dimension.

This whole TDP as defined by Intel/AMD is just a PR gimmick.