Intel is going to ship updated Pentium 4 Prescott chips in May, after sampling the chip at the end of this month. The Prescott update will take the 2.8GHz (533MHz and 800MHz FSB), 3.0GHz and 3.4GHz Prescott processors to a new D0 stepping (currently Prescotts have a C0 stepping). The CPU ID will change form 0F33 to 0F34.
According to the Register the new chips will feature reduced energy consumption and will thus become less hot than the current Prescott processors.
Samples are set to ship on 27 February. Qualification tests are due to be completed by 23 April. Retail product is expected ton 7 May.