I'm a Zeiss ZM fanatic and bought a used 25mm lens three weeks ago. Great lens but, as usual with some WA lenses, it suffers on the NEX-7 with vignetting and a colour cast. However, this can be fixed with a free program called Cornerfix:-
I forgot to mention that I've sold my E mount native lenses and replaced them with Zeiss ZM. Then, when Sony release a new full frame NEX I don't have to go and buy new lenses as the Zeiss image circle will cover the new sensor size.