I thought about it before with plain white LED's due to the fact that they draw much less power than the standard bulbs, but they give a different kind of light. The light is very directional from a LED so it only shines on a small area, so many of them would have to be used and positioned in the right directions for them to work.
I decided not to do it and just put in a little brighter bulb in my headliner light.
I don't like the way that looks with the blue either.
http://www.durangedesign.com/led.html I wanted to go with white face gauges and leds from these guys, but I don't think it is worth the trouble. Well maybe now since my instrument bulbs went out and at night I can only see up to 3k rpm on my tach. Thank God i installed my shift light.