In addition to the 15mm f/2.8 Distagon announced today, Zeiss has also announced a UV filter and polarizer in a 95mm size to fit the 15/2.8 or most any lens with that filter size. Zeiss also introduced a UV filter in 43mm and 46mm sizes for use with our ZM lenses.
Zeiss filters are listed on my Filters Gear Page. The 95mm and other sizes should be listed soon once they enter the retail channel.
I am unsure of the merits of a polarizer on a 15mm lens due to the uneven polarization across a blue sky, but it might be useful for saturating colors on wet or rainy days or for close-ups— which would be interesting given the already high inherent color saturation of the 15/2.8 Distagon.
I don’t shoot with filters very much, but I think if one is going to invest in the 15/2.8 Distagon, then a 95mm UV filter is a smart move for adverse conditions, or for close-range work where there is a very real danger of jabbing the front lens element right into the subject.