Are SMPTE standards used in distribution today? If not, then how is content distributed?

All digital cinema products are designed to meet an informal specification called “InterOp.” The Interop DCP (digital cinema package) is based on early draft standards to promote interoperability in the early phase of the digital cinema rollout. Interop DCP is similar to, but not compliant with, SMPTE DCP. It does not support many of the features incorporated in SMPTE DCP, most notably SMPTE audio specifications. The specifications for both Interop DCP and SMPTE DCP, as recommended by the ISDCF, are listed in the ISDCF SMPTE-DCP Transition Review.