What is a Penryn Processor?

At the center of rumors about new MacBook Pros this week is the Penryn processor, a new Intel processor. What this will mean is a smaller, cooler, slightly faster processor that is a little easier on battery life as well.
The Penryn processor is already in other machines, such as the HP Pavilion.
There is something new in the Penryn, something called “SSE4”. This is a set of instructions built to improve performance when encoding audio, video and images. There is also a speed boost for the Level 2 cache.
There is also a mode where the processor almost completely shuts down an requires almost no power while sleeping, though we don’t know how well new MacBooks would take advantage of this.
For most of us, this just means that the MacBooks will get a little faster, and maybe the battery will last a little longer.