As has been mentioned...they do, sort of...
But the main reason is that the application of such a chip is not really in the personal computer arena. Low power, low-cost embedded processors are used all the time in the PLC/microcontroller fields. However, the architecture of a Pentium 133 is probably not as conducive to the applications required in this field as the newly designed embedded parts that are currently serving this market.
MOST importantly, though, is cost. Development work is one cost, fab cost is quite another. Are we going to reduce the available .13u fab space to run low quantity, niche processors which (in the applications listed) would also have to be priced low, and take away fab space from our current gen CPU's?
While I'm sure porting the platform to other fab processes is probably a good R&D path, it doesn't seem to make a lot of sense from a normal, retail sense.
P-X