I personally don't get the obsession with it myself. Our eyes only see at a rate of 24 fps anyways. I guess to those that care, it's a big deal because it would put console gaming on par with PC gaming, as far as graphics are concerned. Just note, those that obsess and (dare I say it) fanboy over a frame rate are usually the first ones to jump ship on upon the next big release and are the last ones to appreciate good storytelling and/or gameplay. To sum up: It's important to some in the same way matching the curtains and carpet are to a woman.

The 24 FPS thing has been proven false. That claim was made back before we were able to exceed 24 FPS but now that we can push video into a much higher FPS, empirical data shows that you can see above 24 FPS. Some tests have shown some humans can see above 200 FPS. It appears to be something you can train your eye for, so gamers are naturally developing the ability to see higher FPSes all the time. Personally I think 48 FPS is where the differences start to break down and become negligible. I can't see any difference between 48 and 60+FPS. I think reaction time is a "bottleneck" of sorts as well. Even if you have developed the ability to see more frames, can you react to a frame that only appears for 5ms (200FPS)? At the end of the day though, the difference between 30 and 60 FPS is large and noticeable. One is serviceable, the other is akin to have your eyes massaged. It's smooth as silk.

Not to sound like a jerk, but could you source the claim that 24fps isn't the limit for us? It's the first I'm hearing of it, that's all :-/

There is a study involving fighter pilots. . But I can't find it right now :( The included link has a lot of good details however.