Some of these TV's actually can sync to native 48 Hz. Many years ago, I used to run a projector at 47.952 Hz (double the 23.976 Hz refresh rate) to create the equivalent of 2:2 pulldown.
Unfortunately, no Blu-Ray formats or players can output at 48 Hz. The only way to do so is from a PC at this time. This limits you to movie files.
Also, several 3D HDTV's accept 60Hz/60Hz frame-sequential *input* anyway (60 Hz for each eye = total of 120 Hz), even though few sources can support that.
Coincidentially, the existence of latent 60/60 frame-sequential support in HDTV's, also makes them over-clock friendly to native 2D at 120Hz, since 3D stereoscopic at 60/60 frame-sequential essentially looks like a 120Hz 2D signal. See HDTV Refresh Rate Overclocking HOWTO: 120Hz from PC to TV.
This same HOWTO can be used to underclock refresh rate to 48 Hz -- from PC to HDTV. And then play a 48fps file stored on a computer. Several modern displays are multi-refresh-rate capable. It works on some displays and projectors. As I mentioned -- I've done it before on a projector...