How legal is it to have a blue light in your turn signal housing? I mean, the LED is probably pretty dim, and in theory shouldn't go on when you're driving (unless you arm your alarm, of course). Might want to check with local state/provincial laws, though.
Also, this probably wouldn't work well on the stock alarm system, since the light seems to flash every 30 seconds when I'm driving. Unless there's a way to disable that that I'm not aware of.
Though in general, it's a cool idea. I never liked how most lights seemed to light up the entire cabin. Only a well-placed light behind the rear-view mirror seemed to not have this effect.