Comment 53 for bug 12637

Some more observations:
I downloaded 8.04 and made bootable CD; started fresh live instance from CD. The screen is dark. When I do a first move with touchpad, though, it suddenly jumps to ca 57%. As I already said, the brighntesss Fn buttons don't work, so I use Gnome applet to change brightness to 100%.
I tried to boot also live 7.10 for comparison. The brightness seems ok, but it is hard to say precisely, becuase function keys does not work, and Gnome applet does not work at all.

Fortunatelly, after upgrading to 8.04 I have choice to run also old kernel 2.6.22-14. This kernel runs very well, brightness is ok (though Gnome applet does not work at all, but I don't need it, because brightness is ok).

When now (after booting with old kernel) I tried to run the new kernel, initially brightness was ok, but during loading (somehere around message "loading hardware drivers" - in disabled quiet mode) it fades (not instantly, but slowly - it takes about 1-2 second). Then restart again, now select old kernel - and during loading birghtness goes up at some moment (again not instantly), but this time much after "loading hardware drivers". But please not that the change of brighntess (also manual) seems always delayed, so it is really hard to say what was the trigger.

To put it simply: whenever I run new kernel, it fades brighness somewhere in the middle of loading progress bar (very not-precise). After restart, even manufacturing screen is dimmed. It is until i run old kernel - birghtness go up then during start, and stay high until I run new kernel (manufacturer logo is bright too at restart after running old kernel).

Hope it helps.

BTW. It is really strange for me that such big bug came into LTS version of Ubuntu. Very disappointing.