I'm afraid the Blu-Ray specs are really rigid when it comes to frame rate (and they don't include 48 FPS, since nobody was using that until now). We've got 23.976p, 24p, 50i, 50p, 59.94i and 59.94p. 50 and 59.94 come from old TV systems (PAL/SECAM and NTSC). Blu-Ray 3D uses the same frame rates as Blu-Ray 2D, it simply encodes separate streams for both eyes.
Displays can have higher refresh rates (like 120 Hz or even 600 Hz) to avoid telecine judder when displaying 24p (and usually have a frame interpolation chip - the aforementioned "TruMotion" thing), but Blu-Ray discs don't encode video at such high frame rates.
You could speed up 48 FPS to 50. In PAL/SECAM countries, a similar speedup is used to air movies on TV.