This technique has been dubbed the "Sliding Doors" and the orignal article and code can be found at A List Apart. While there are no ground breaking refinements here, the examples have been modified to suit my purposes.
In the first example, only the straight css is used (no hacks or conditional comments, etc.). The tabs will only display correctly and display the proper hover behavior in modern browsers which fully support the css2 standard such as Firefox and IE7 (mostly).
The problems arises for those of us who have to code for the real world. Unfortunately older versions of Internet Explorer do not support the CSS2 standard as well as everyone would like. With the market share that IE6 and below still hold, it is not smart do develope sites which do not display correctly with these browsers.
My normal approach to the IE problem is to write as pure CSS as I can and then fix any problems IE might have with conditional comments.
Example 2 This example uses an extra span in each list item in order to accomplish the highlight.
Example 3 This example uses IE's comments to apply include specific rules for that browser only. The navigation list is contained inside div tag (this causes a slight change to the css).
Example 4 This example uses IE's comments to apply include specific rules for that browser only. The containing div has been removed. Note that is no apparent change to the look of page, this may be attractive to thost interested in minizing markup (others may need that hook for some other stlye concerns).
Example 4a This is the exact same coding as Example 4 with the exception that the body tag id has been changed to id=about vs. Example 4 where id=news.