I just recently did a fresh install of Fedora 16 (3.1.4-1.fc16.x86_64) on my Thinkpad X120e and I'm having trouble with dimming. The function keys still seem to work, but it appears to be a software problem (the function keys worked on Fedora 15 as well, but actually lowered the brightness).
At any rate, the brightness "overlay" shows up in Gnome (3.2 on Fedora 16, right?) and lowers the brightness a single tick on the graphic (but not at all in reality). Repeatedly pressing the "lower brightness" button doesn't lower either the bar in the graphic or in reality. Moving it up only changes it in the graphic back to full.
Using the "screen" setting (GUI) and dragging the bar for brightness left and right doesn't do anything.
I also installed the "xbacklight" application and it doesn't change anything either (and exits without error).
Not sure what else to try, but I'd really like to be able to lower the brightness. Any thoughts, help appreciated. Please let me know if there is any output that would be helpful.