Wow! Sintel is making available a 4K intermediate version of the short animated movie. The current version is stored as an 8 bits per pixel TIFF sequence that weighs in at 160 GB. They are in the process of uploading a 16-bpp version that'll weigh in at 650 GB. The frame dimensions are 4096x1744, which is 2.35:1, a little narrower than CinemaScope.
I'll be downloading these intermediate files and packing a 4K resolution DCP for use at IU pronto!