Ultra sonic cleaning is only used in immersion baths.
Well, that's what I thought, until about a year ago.
There is a method where a small transponder is applied directly to a stain - it's rather like an ultrasonic toothbrush, but incorporates other bits if kit that make it less than easily portable.
Details are sparse and some of the (very little) information I have was passed to me in confidence, so please do not ask me for more.
This product is in the development stage, so if they can get it to work and onto the market at a viable price, I expect will will hear more in a year or so.