What projector can accept 48fps via hdmi?

Probably none, unless you're talking about commercial setups.

What are you going to use to playback a 48fps movie? Blu-ray doesn't support it either.

Based on some comments in the forum I think the Sony Ruby did. I have an Optoma hd81lv which has an undocumented 24sf mode (and no regular 24fps mode), but I use it with an htpc and feed it progressive 48Hz and that appears to work. Neither of these are current models.

I was looking at AH about Dolby Atmos
http://www.audioholics.com/news/editorials/dolby-atmos

The new movie being filmed in New Zealand, The Hobbit is in 3D AND, 48 fps
Perhaps the new video format of tomorrow?

Blu-ray supports it at 720p. The problem is that even if blu-ray supports it at 1080p there aren't a lot of HDTV's and projectors that support it. iirc there are a few plasmas out there that currently support it and maybe a few LCD's but because there is no mainstream demand for this frame rate companies aren't going to spend the money to incorporate it into new technology if there's no demand for it. They sure as heck won't do if only a couple movies come out in that format. What we'll be getting on blu-ray for The Hobbit is 24fps. They achieve that by giving us only every other frame.

Though this is just an assumption, but I'd think almost any 3D projector could do it. 1080p24 Frame Packed is effectively doing 48 fps, just half for one eye, half for another. As far as the projector is concerned, it is just displaying those frames at 48 fps (or 96 fps, or some other multiple) and letting the glasses do the work of sending one to each eye. If you just sent a 2D image encoded as a 3D image, and left off the glasses, I'm betting you'd get a 48 fps image on screen.

The main issue there is all the projectors that lock you into a 3D mode with a poorly calibrated image to get more light output, but if you can force a normal display mode with a 3D signal, I don't see why it wouldn't be possible.

Answer: JVC HD10

I suspect that quite a few projectors can accept 48 Hz inputs (or 47.95 Hz) in 2D (my 3+ year old Epson 6500UB can) via HDMI. However the real issue is frame packed 3D at 1080p/48 (with 48 unique frames for each eye, each second). At this point there are no sources that support this and the first commercial movie being shot at this frame rate (the Hobbit) has not yet been released in theaters. Avatar 2 and Avatar 3 will also be shot at a high frame rate, certainly at least as high at 48 Hz and perhaps as high as 72 Hz. The current HDMI standard (ver. 1.4a) defines the following full resolution 1080p 3D frame packing formats (other formats are not listed below):

Mandatory 1080p frame packing 3D Formats (required for all HDMI 1.4a 3D displays)

1080p @ 23..98/24 Hz

Primary 1080p frame packing 3D Formats (required + optional)

1080p @ 23.98/24 Hz
1080p @ 29.97/30 Hz

Secondary 1080p frame packing 3D Formats (additional optional formats for which the HDMI 1.4a standard defines the signal timing requirements)

1080p @ 59.94/60 Hz
1080p @ 50 Hz
1080p @ 25 Hz

Right, nothing out there now is going to take 48Hz 3D content that I'm aware of, as it's not a standard. Additionally, that's going to be 96 individual frames per eye, per second, and is going to cause some more serious brightness issues I would suspect. Even something like the SIM2 that uses the DLP TripleFlash tech (144 frames per second) can't do a multiple of that, and so unless you have a passive 3D stack from Runco, you're going to have some seriously dim images.

Of course, you also need Blu-ray to feed you twice the bitrate of a current 3D film to pull this off as well, and given the current bitrates of film and the specs on Blu-ray, we're looking at issues with compression and disc size as well. I'm pretty sure we won't see 48Hz 3D at home for a while due to those. Now if they want to put out a 48Hz 2D one that uses frame-packed 24p to pull it off, that would be very interesting I think. They can make it a bonus disc in the 3D set and say it needs a 3D TV, but to not use glasses. I'd be interested to see if that works.