...Under normal operating conditions.
Therein lies the rub. But the way the processor's designed, it realistically won't hit it's full power consumption with existing synthetic tests, like Prime95. The deal is that it shuts off parts of the processor between clocks, so that it remains cool despite operating at full tilt.
Just the same, Intel doesn't count a double-run of Orthos as "normal" and you can realistically pull 125W for the workload with a non-overclocked Q6600.
It's a bit dated, but neither Intel nor AMD has since changed their methods for determining TDP:http://www.silentpcreview.com/article169-page3.html
Intel is listing TDP numbers that are significantly lower than the actual maximum power draw of their CPUs. They are then relying on the fact that most applications barely use the CPU, assuming that it will remain idle most of the time. In the case that an application does max out the CPU for any period of time, Intel relies on their Thermal Monitor to automatically slow down the CPU when it becomes too hot to protect it from overheating.
AMD, on the other hand, lists TDP numbers that are significantly higher than the maximum power draw of their CPUs. They also have listed the SAME TDP for every desktop Athlon 64 so far, and I have little reason to believe that future Athlon 64s will have a higher listed TDP (at least for the near future). We still don't have definitive information about the exact power dissipation of each of the Athlon 64 processors, but it is clear that other than the fastest clock models, it is far below the 89W TDP cited by AMD.
The 45nm parts are significantly improved over the 65nm with regards to idle power and power management (AMD, 'til that point, was still beating Intel over idle power consumption, and that wasn't going to last) and at the low end of the frequency scale, operate well below the TDP prediction (which is based on the highest possible clock speed of the series) like with what you saw with your E8200 (I have an 8400 that maxes out (with SpeedStep enabled) at 47W).