Question: I tried this with DIVs. The problem occurs in both. I can't get the right border to be equal heights as the longest DIV. And I need this to work across the current desktop browsers from the days of IE7 and up.

This is a common problem, but it's 2011 now when I write this. Is there finally a way to do this with pure cross-platform CSS without resorting to funky tricks like pretending to make it work (such as a column cutoff)? Or, must I resort to jQuery to make it work in the least amount of fuss?

**EDIT**: My bad. When I wrote this originally, I included TABLE TDs having the problem as well as DIVs. But I didn't realize that I had taken my test code and switched from DIV to TD, but my CSS still said float:left;clear:right. When I eliminated that with the TDs, the border extended to full height of the longest column. However, still, it would be good to find out how to do this with DIVs, but cross-platform from desktop browsers starting with the year IE7 came out and upwards.

Answer: 
A quick way to get the effect is having a background image with a segment of your border on your container div that repeats down the page. This will make the border extend as far as the parent container which should be the tallest column.

Hope this helps.
Could you provide a URL for your page? BG images would work if your markup was a certain way. I'd love to take a look at your page to see what you're trying to do.