I think so, but not in the traditional 'prog-rock' kind of way. When one thinks of Progressive Rock, they tend to think of album-side long heavy jams like Yes did, King Crimson's soundscapes/noise, etc. But I do believe that The Beatles with their experimenting with different sounds, from a 12 string Rickenbacker, Sitar, backwards loops, orchestra, etc, were definitely progressive rock. Their music kept moving forward in a mighty way. I assume they aren't considered progressive rock is that they kept their songs (for the most part) under 4 minutes and didn't engage in jams that went on forever.
