While I was looking at this product, as it being a thing that I might soon buy, so as to mount a second monitor on my desk, then I noticed this review. Specifically, then, I noticed the comment about flat-panel displays that can rotate into portrait mode. I wanted to mention, in the market interest: The HP w2408h can rotate into portrait mode, itself, and the support software included with the monitor will automatically update the display, once it's rotated. It's not a terribly pricey monitor. I expect that these features would be available on some HP monitors of other sizes, as well.
(Granted, I'm not sure how the HP software features would be affected, once the monitor would be mounted to a third-party mount, but I'm sure that HP has taken the likelihood of such a configuration well into consideration, in designing that software.)