Here's the scene file. It was made in Maya 6.5 .

Lava scene file


Here is a different look to the lava



If you like this one better then use this file:

Lava2

I gave you some wrong info when I said that the incandescence was driven by temperature. You could do it that way but in this example I chose to use a Y gradient for the incandescence. I also animated the texture so that it would move as the lava moves. If you want to play around with changing the look of the lava, go to the texture settings under the fluid container and experiment with the amplitude, ratio, and frequency ratio. Also try the texture setting while you're there...

Have fun!