My Mother In Law Fancies Me, Should I Risk Doing Anything About It?

My mother in law is in her late fifties, I am in my early forties and I have known her for twenty years. She has always been very welcoming when we have gone to stay at her house and I knew she liked me but thought it was just as a son in law. Then my wife started to drop hints to me about how my MIL thought I looked really well at this family function or wedding or whatever. The she tells me that when my MIL had been looking at some pictures on facebook of me and my wife at a recent wedding she thought I looked "georgeous". My wife then said, I reckon she fancies you. I told my wife to stop as i thought the idea silly and a bit off putting. However having thought about it a bit I can see the attraction of sleeping with your MIL, its a bit like the idea of sleeping with your sister in law which most men have except a bit more extreme. My question is what, if anything, I should do about it?