At first I was quite sure what you meant by 4 columns, I was a little nervous about clicking the link! Now I see what you’re referring to, and so have the lovely CSS Gods. With CSS3 you will be able to achieve this exact thing without using multiple divs, hurrah! But in the meantime (for cross-browser compatibility), some nice folks have provided a Javascript option.
Gives this article a read, it should provide you with all you will need to know: http://www.alistapart.com/articles/css3multicolumn (includes a link to the Javascript option).