Rainbow Fall, in Devils Postpile National Monument, Eastern Sierra, west of Mammoth Lakes.
Taken about 4:30 p.m. Saturday 6/7/08. Even late in the day the fall reveals its namesake. Kinda lucked out, it was mostly cloudy during the hike down there but the sun popped out just in time for a photo op.
Higher res image here. One of these days I'll make my way up to Tioga Pass and the meadows again. Gotta save more gas money.