This idea came to me almost the same day I got a1200. Then this question was brought up in motoezx conference. So here it is, lightsensor daemon that makes your camera work as light sensor which is missing in A1200. Checks your camera every 5 seconds and adjusts the backlight appropriately.
Usage: lightsensord [-d] [-f] [-m level] -m level Set minimal brightness level (0..100) -e level Set brightness level on camera open error (0..100) -d Debug mode -f Run in foreground
Source code and compiled binary for a1200 are available here: lp:~rye/+junk/lightsensord-0.4 (updated). Version is 0.3 at the time of writing. The motofan.ru thread for this app is here: http://forum.motofan.ru/index.php?showtopic=147528.
May your screen be always readable :)