In a web browser where not much vertical space is available (such as my bosses laptop with IE9 and a couple toolbars installed), when the new review dialog is shown from the activity feed, the "Request Review" and "Cancel" buttons are off the bottom of the screen and cannot be scrolled to, making it impossible to request a review.
I've reproduced this issue in both IE9 and Chrome 8 by simply using the web browser in a smaller window. (On my machine, the buttons are inaccessible in IE9 when the window is around 600 pixels tall. If toolbars were installed, it would be worse.)