I'm not an expert on material use, but I think you could use a volume material for the 'head', with a pretty transparent material for the beer. then tiny metaballs inside the beer for carbonation. It's going to be a lot of metaballs! Not sure about the condensation - maybe do it in post? You could maybe do a separate render of the beerglass alone with a volume material on it, and blend it afterwards in Photoshop or whatever, rubbing out the sections of condensation material in the areas where you want the clear glass to show through. Agent Smith would be the expert on this subject ;o)