This is a quick rundown of how and why we use YUI3 grids at App.net
As far as I can tell there are three types of CSS grids: a static-width pre-defined grid, a flexible-width pre-defined grid, and a generative grid. In the first two grids (pre-defined width), you basically decide how many columns you have across the screen, and then create blocks in any multiple of those. This pattern often looks like "span-4", "span-6", "pull-10", "push-5", etc. You find this style in popular frameworks like Bootstrap and Blueprint.
The third way, the generative/recursive grid system, doesn't seem to be as popular as the others. I am not entirely sure why, because the generative grid can pack more punch in less lines. In this vein is there is OOCSS and YUI3 CSS Grids.