The Edges of Meaning
Although we're moving toward more meaningful markup and naming conventions within HTML, XHTML and CSS (as this discussion shows), we're also starting to run into limitations of our imaginations and the specifications themselves.
Many folks have argued that HTML and XHTML are limited in their capability to truly be semantic, and that alternatives—such as creating a vocabulary on your own with XML—remove these limitations. Although that argument is true in theory, in reality those of us who are designing primarily for the screen will most often be using HTML and XHTML. So we do the best we can for today as we stand here on the edge of change and we wait for a time when we can be far more flexible in a more semantic future.