As everyone mentioned, it might not be a good idea for layout purposes. I arrived to this question because I was wondering the same and I only wanted to know if it would be valid code.
Since it's valid, you can use it for other purposes. For example, what I'm going to use it for is to put some fancy "CSSed" divs inside table rows and then use a quick jQuery function to allow the user to sort the information by price, name, etc. This way, the only layout table will give me is the "vertical order", but I'll control width, height, background, etc of the divs by CSS.