film programs appear to have a very slight neutral density filter applied

You mean they are slightly darker [than HD content]?

35mm film until fairly recently didn't come close to today's Sony F900 sharpness.

HD shot on Sony [1080i] cameras looks much sharper than say Panny [720p] HD footage. I have reviewed these side-by-side extensively, and believe the difference in perceived sharpness is mostly a creative choice by the respective manufacturers.

Sony came from a distinguished history of being a leader in broadcast studio cameras, where sharpness was very highly valued [and interlacing was an article of faith in the broadcast TV world]. Even when they created a feature film-specific camera in a joint venture with Panavision, Panavision's engineers found it impossible to get Sony to accept all the differences required to create a true film-replacement camera. I heard a lot about that when I was at Panavision to check out their cameras for a production ($3,000/day, a good chunk of which goes towards their checking every aspect of each rental camera before it goes out, and I saw nothing remotely like even the slightest sloppiness in this work, very impressive indeed).

Panasonic didn't have this BCTV studio background to tell their engineers what was "right" and what was "wrong". They just decided to create a camera that was as much as a film camera as possible, and this shows in the output of the Varicam series cameras.

I personally like the way Sony broadcast cameras work, their consistency in operation between different models, the many nice touches that make the work easier, and lots of choices that could have been made worse but were not. Still, I hate interlaced video, and it doesn't look like Sony will abandon this completely until their last television engineer has been laid to rest, hopefully voluntarily :O).

Anyone who wants to really see the difference between 35mm as it used to be and today's HDTV, just check out any TV series from the '60s or '70s (they were all produced on 35mm, because 16mm wasn't even close and video recording was a pathetic joke. The 35mm sharpness didn't even match today's Super 16, and the grain was often quite visible. Shadow detail was readily available, as long as there were massive lights to help...

Film has come a long way in the last few decades, and HDTV production is now going through the same rapid evolution as film thanks to an ever-expanding dynamic range, larger sensors, rapidly improving DSPs, better lenses designed with new materials and faster computers to calculate more rays, etc., etc.

Still, even say 5 years from now, there will be people using the very latest and bestest HD equipment at that time who will go see an IB Technicolor (3-strip) 70mm revival at a good theater and get a big lump in their throats. Somehow this creates a very powerful, 3D-like image that is something very very special and grabs you by the throat emotionally. It's something beyond "sharpness" and other objective parameters. I sure can't explain it.