I made chocolate curd last night. Same basic recipe but I used unsweetened cocoa powder and some splenda sweetened chocolate chips (Mini-carb, Netrition has them).

Doing this in the microwave is harder than it seems. You really have to do it in short bursts (like 15 seconds), watch the temperature like a hawk. I think the double boiler is actually not difficult at all and results in a better.

So far my microwave attempts have almost curdled on each occassion. They definitely don't have the smoothness of the double boiler method.