I havn't been able to take a good look at that coffee shader at highend, but I believe it is a layered texture or shader, and comes with a "bubbly" image that goes on top. ( I think)

...at least, that's the way it looks in the sample pic.

Thanks for the help Emo!

Yeah, sometimes folks underestimate the power of sprites, and when they are raytraced, they look even better sometimes

Keep going in the direction that you are going, and you will be fine