I've only recently come across the technique myself. I think the hype is because it is new (well new in old new thing kind of way). What I find interesting is the duality like relationship between MCMC and variational methods. Variational methods are an optimization alogrithm. I don't understand variational methods enough to say anything insightful but given the work showing the duality between optimization and probability* I find this new development of hype to be highly interesting.

Drawing on the concept of duality, I think Variational methods will come to be seen as holding no more power than probabilistic techniques. But a Duality is still great cause you can plumb old techniques to get new results.

*http://www.cmap.polytechnique.fr/~akian/publis/akian_quadrat...