I'm been getting the airbag light 80% of the time in the past couple months. This weekend I took the overhead panel apart and soldered the little board back together. No light this morning on the way to work!
Edit: I snapped a few pictures while fixing mine, for anyone who worries this repair is beyond them.
1. Remove the map light cover (pry on the sides with your finger nails)
2. Remove the two philips screws holding the panel to the roof.
3. Remove the panel (it has 3 prongs that hold it against the headliner on the front edge)
4. http://img.photobucket.com/albums/v252/crazy_pilot/2008%20Legacy%20Spec%20B/IMG_1214-1.jpg
5. http://img.photobucket.com/albums/v252/crazy_pilot/2008%20Legacy%20Spec%20B/IMG_1213.jpg
6. http://img.photobucket.com/albums/v252/crazy_pilot/2008%20Legacy%20Spec%20B/IMG_1210.jpg
7. Re-solder any other components you feel like. I did D1, R1 (the 511 guy), and all the resistors on the other side.
8. Put back together!
You don't need much experience soldering to take care of this, I've only done it a few times myself. Let the iron heat up, melt a decent amount of solder onto the tip, shake/tap to remove the excess, and then place the tip against the joint you want to fix. Once the board heats up enough the solder will flow down. I basically filled the corners with a nice little dot of solder on each one.
Second edit: I'm sorry if that last picture is sideways, Photobucket shows it straight and then upside down if I use the "rotate" function. Meh.