Well, this thought never really came to mind till the European crisis. There are many comparisons between how EU is not an optimal monetary union (as in lacks the main features of a mon union – labor mobility, fiscal union etc) and how US is closer to the optimal mon union. (see this and this for some recent discussion). Canadian Blog pointed to some comparisons between CMU and EMU as well
But what about India? How does India fare as a monetary union? Barring some posts by Gulzar there is hardly any mention of bringing this monetary union debate in India’s context.