Oscar Casamitja patched the old rotate program to change brightness on rotate in order to better hide xrandr’s artifacts. That’s actually a very good idea.
This new version reads from actual_brightness and set into brightness, which you can find in /sys/class/backlight/pcf50633-bl/ , in order to skip packet reading when the screen is dimmed, which is the next best thing to checking wether the screen is locked.
I run into a problem, though: it seems that if I open() actual_brightness once, I never again read an updated value, which makes me have to read on every loop 
Enough talk, get it here: rotate-0.3.0.tar.gz (ascii sig) [now, if only this bug was fixed on projects.openmoko.org...]
Hope you’re enjoying it… 
$ head -2 ChangeLog 2008-10-14 - 0.3.0 * dims while rotating and doesn't rotate if dimmed, sleeping for 5s $ cat KNOWN_ISSUES Known Issues: * I'm not getting updated results if I only open /sys/class/backlight/pcf50633-bl/actual_brightness once which means I need to open it on every cycle. Since it's in memory and not an actual file, wast should not be too much * some heuristic values may need fine tunning
#1 by Sebastian "stein" Billaudelle on 14 de Outubro de 2008 - 22:06
Wow! Great tool!
Maybe one point: I think it would be better to rotate the screen after holding the Neo one second after turning it. At the moment sometimes the screen rotates if I shake the Neo…
Thanks for this tool!
Sebastian