Ian wrote about, and implemented, what he calls human-friendly URLs.
Previously I had used the /year/month/slug pattern typical of many WordPress blogs, i.e. http://ianhin.es/2010/12/designing-urls-for-humans. This is the same pattern used by the likes of Shawn Blanc, Ben Brooks, and, John Gruber (although Gruber uses Movable Type, not WordPress).
But, if you think about it, these URLs really beg the questions: why do I care what year and month the entry was published in? Does it really matter? The answer is no, it doesn’t. At least not to me.
I copied this idea of his, as frankly, I too find it a bit redundant the way WP normally creates permalinks.