It's also worth noting that many camera sensors have a filter in front of the sensor itself, called an "anti aliasing filter". It basically blurs the image projected by the lens onto the sensor - a bit batty if you ask me - but essential in order to avoid or reduce moire patterns with certain types of subject/background.
When you shoot to JPEG the camera's own internal processing will usually sharpen the image data before it saves it to a file (unless you disable in camera sharpening). When you shoot to raw there is no sharpening performed in the camera, so no matter how sharp your lens, or accurate your focus, or steady your aim, or high your shutter speed, the image will be soft. Thus when you shoot to raw you should fully expect to sharpen your images before finalising the image for print or other display. Some raw processors will start out with some default sharpening, such as Lightroom, while others may not. when you shoot raw you get to choose how much to sharpen, and how exactly to sharpen, in your raw software. You don't have to be constrained by what the camera spits out when it saves to JPEG.
Furthermore, when you resize an image to make it smaller, all those fine edge details get splatted together and any sharpening you might have performed earlier in your workflow (including sharpening by the camera if you shoot to JPEG) pretty much gets thrown out with the bathwater. Thus your very last step, after all your edits, resizing etc. is to (re)sharpen the final image before it is ready for display. Some software might do this for you while some may not. In Lightroom 2, for example, there is an option when you finally export/save an edited file to sharpen it one last time as it is resized and saved/exported.
p.s. some people actually have their cameras modified to have the AA filter removed. See this page, which does explain and demonstrate the effect of AA filter removal -
http://www.maxmax.com/hot_rod_visible.htm
p.p.s Some people actually have three sharpening stages in their workflow....
1. "capture sharpening" to basically counter the effect of the AA filter; if using Photoshop you might do this in ACR first, before opening the file in Photoshop for artistic editing.
2. "creative sharpening" to enhance the image as necessary to make it pop etc.;
3. "output sharpening" which is the final sharpening step after resizing and before saving/printing. (sharpening for print should be more aggressive than sharpening for screen display)
. So although it is a trick, there is sound science behind it - i.e. the science of how the human brain perceives images.