A brief note on the evolution vs. intelligent design/creationism (they are pretty much one and the same) thing going on in various parts of the blogsphere (interesting timing, considering Stephen Jay Gould's recent and untimely passing).
First is what I'm going to call Evolution for Beginners (in other words, this is the level that I understand it at).
The first part of evolution is the process of natural selection. Natural selection is really very simple: given two different organisms, the one that's more suited to life in that particular environment is more likely to survive (and by extension, pass on its genes to the next generation). That's pretty commonsense. We can all agree on this, right?
The second part of evolution is genetic mutation. Genetic mutation is what gives us the differences between the organisms that we saw in the above paragraph. Some mutations are beneficial to a species; for example, a mutation to be taller would be useful for a species that lived on a plain or prairie (you'd be taller, so you could see farther). Some mutations maybe be detrimental to a species; a mutation to grow heavier fur would not be an advantage for a species that lived in a hot desert (you'd be hotter and less able to cool yourself). Conversely, though, those mutations may have the opposite effect, depending on the environment: being taller wouldn't do you much good if you lived in densely overgrown jungle (you'd be less agile); having a heavier fur coat would be a good thing if you lived in a very cold place. Sometimes mutations are neither a benefit nor a hinderance: there is no particular benefit conferred by being either right-handed or left-handed.
Take the two mechanisms of genetic mutation and natural selection, add a few billion years, and you'll end up with pretty damn complex and interesting organisms (namely us). For more on how these two perfectly natural processes can combine to create incredibly complicated things, you should read The Blind Watchmaker, by Richard Dawkins.
It's really rather simple, and is, in fact, testable in the laboratory on a small scale. There's no requirement for any intervention by any outside (or higher) power.
On the flip side, "Intelligent Design" stipulates that a higher power designed us by 'guiding' evolution. Unfortunately, there's no particular requirement for a higher power. Evolution can do the job just fine by itself. Here, "Intelligent Design" fails Occam's Razor in spectacular fashion.
The interesting thing is that evolution (or indeed, any science) does not disprove the existence of God. The very nature of deities is such that they can never be proven (by us); conversely, they can never be disproven. What evolution does prove is that, assuming the existence of God(s), He/She/It/They did not take an active role in our development.