The Inquirer recently talked to Intel who confirmed that current revision of the Prescott does have high dissipation and that 100 watts was close to that number, while they are already working on a new core revision that could cut this dissipation.
We also saw a slide confirming 11 new instructions, an 800 MHz FSB mPGA478 package, 1MB of L2 cache, hyper threading enhancements, and that it used Netburst marchitecture. We also saw a picture of what appears to be the Prescott core.
Intel's Prescott (code-name) is rumoured to be the processor that will become the Pentium 5.