Asking "would you like your eggnogg warm" is a good way to get yourself shot in some parts of this country. For example, I've been told that in Montreal you can only serve eggnogg at a temperature of 6° Centigrade; anything more will be deemed a strict offence to national/francophone/local pride. (The offence would be comparable to that of serving cold poutine to a Québécois.)
The other side has its own (very reasonable) arguments. In Winnipeg, the preference is for eggnogg fresh off the stove; this imperative seems grounded in the historical "Eggs 'n' Grogg" history of the drink. A likely source of continued influence in this area (now that grogg is almost unheard of as a wintertime drink) is the Mennonite imperative to live a life of tradition and domestic comfort without submitting to worldly culture shifts.
A more recent trend in eggnogg-consumption comes from the italians (or from Seattle, to be more precise...): for an eggnogg-based café latté, simply replace the normal quantity of milk with fresh eggnogg. (The chain-café uses eggnogg 2:1 with whole milk.) I've yet to experiment with ratios of cream to froth, but I would imagine that the low-fat versions of eggnogg will see a similar increase in yield to that of skimmed milk over whole. Another area of necessary research is in the result of steaming raw eggnogg as opposed to the "cooked" versions. (Eggnogg rarely contains raw egg these days, as most recipes prepare it like a thin custard.)
Personally, I take the side of our Lord:
So then because thy eggnogg is lukewarm, and neither cold nor hot, I will spue it out of my mouth.
Refridgerated or Steamed, I like eggnogg quite a bit
Lukewarm eggnogg? To drink it is not fit.