Honing vs. Sharpening
The first thing to clear up is the difference between honing a kitchen knife and sharpening one. When most people at home use a "honing steel" or "butcher's steel," or that long metal rod that comes in the center of a knife block, to "sharpen" their knives, what they're really doing is honing them.
The difference is that a honing steel straightens out the blade of a knife, making the edge straight and ready to use. As you use a knife, the tip of the blade will eventually bend and curl so you don't get a real blade-on cut at the very tip. The best you can really do at home is to hone your knives regularly to keep the cutting edge straight – for most at-home cooks, this makes the knives "feel" sharper. Check out this video at Chow for a visual description.
