I’ve had a few cases where I use the class attribute of an element to rig javascript, only to find that later someone has “improved” the page, changed all the class names, and broken my javascript.
456 Berea St. has a nice post about how the class attribute encompasses more than just CSS.
I’ll also add that microformats are pretty much based entirely on class names being correct. I’ll leave the debate over their utility to others.
