Indeed. It's got nothing whatsoever to do with if the camera is film or digital, purely with the way it gathers light for the AF and/or metering systems. Systems that use beam splitters/semi-silvered mirrors can be confused by linear polarisers - that's virtually all AF SLRs, film or digital, and many other SLRs with spotemeters or multi-pattern meters. Some people report success using linear polarisers with such cameras, but I wouldn't personally take the risk. A polariser will act as an ND filter, but you could consider a non-graduated ND filter.