I actually bought the mouse when it first came out, so I have the old revision.
What it means by improved optical technology is that the DPI has increased, so now it compares with a lower model Boomslang. Here are some number I'm gonna throw at ya. A Razor Boomslang comes in two flavors the last time I checked, a model with 1500 DPI (DPI=Dots Per Inch) and another with 2000 DPI. The first release of the Intellimouse had a 1200 DPI, and the newer release has 1500 DPI. Now it compares with the lower model Boomslang, and by my calculations, it's only 25% more 'accurate', not faster. It's only faster in the sense that the optical 'eye' updates faster, which it may. If so, then I'm just running circles around myself...lol Sorry.
So, for the record, the Boomslang is the champion in precision, but at a higher price, of course.
For reference, a regular PS/2 or USB wheel mouse has around a 600 DPI. If I am wrong about any of this, someone please correct me.