Answer:
SMP stands for Symmetric MultiProcessing, and it refers to having muliple processors (or cores) in a single computer.
Most modern computers are coming with dual core processors, which essentially means there are two processors on one chip.
This allows the computer to do more than one thing at a time. In single processing environments, the computer can really only do one thing at a time, but it will have a queue of many things that need to get done, and it will switch between them, to give the illusion of doing more than one thing at a time. So, if you have 2 cores, then the computer can do 2 things at a time, and it will switch between the items in the queue, while working on two things at once.
It seems that new advancements in chip technology are focusing on getting more cores on a chip, rather than making the processor faster. Then end result is the same, though: your computer and applications are more responsive.