James Poniewozick may be right that "Jack Bauer is the new Janet Jackson", but I'll take issue with the statement that "a f___ is a f___" in terms of obscentity. I don't doubt that in the eyes of the FCC (at least at this point in time), that statement is true. But TV writers are nothing if not creative. Can't say "f___" on television? Just create a stand-in that starts similarly, and have the cast say that word as if it were an invective - voila! - instant curse word.
Generally, this approach is most popular on science fiction shows, but I've noticed a bit of bleed over into other shows that chafe at the squeaky cleanliness of network television. "Veronica Mars" seems particular fond of BSG's "frak," which has so much of the harshness of "f___" that I'm kinda surprised they get away with it (especially on the CW or when a couple of episodes of BSG aired on NBC).
I guess so long as the FCC is content to regulate only the objective terms themselves (s___, f___, etc.) it will be safe to fake-cuss. I suspect that they might not have a choice under the First Amendment, whatever the PTC might think. To me, this is a relief, since there are many shows on television where "darn-diddly-arn" as a cuss word just won't cut it.