While driving in to work this morning, I head the reporter on NPR talking about a sense of "palatable relief" on Wall Street due to the bail out of AIG. After I finished snickering, for which elitism I will soon, doubtlessly, be punished by the law of prescriptive retaliation, I googled the phrase. It's not very common (only 100 g-hits as opposed to 8080 for 'palpable relief'), and a few are just accidental collocations crossing phrase boundaries, but clearly this is not unattested. Interestingly, the phrase shows up not just in semi-literate fan-fiction, but in Google books. Here, most of these instances are not mistakes at all. Palatable really is intended in one of its core senses. The following is from Samuel Naylor's 1845 version of Reynard the Fox:

from that instant, however, "the secret force of fascination (as old Thomas Fuller aptly expresses) did cause the sparks of the author's wit to lay hold on the reader, and inflame him with a desire of love, liking, and imitation:" and shortly afterwards meeting with the Low-German Rynke der Voss, bearing the name of Heinrich von Alkmar, the meditated project was seriously commenced, by way of palatable relief to studies of a less trivial nature.

Such instances make me think that the NPR reporter might actually be forgiven her usage. After all, by one way of looking at it, you could say that the U.S. government's bailout of AIG was really more palatable to financial types than the alternative. Still, given the much higher frequency of "palpable relief," it's hard to avoid the conclusion that there is some eggcorn-like confusion going on here. I can't be so forgiving of another instance that shows up in Google Books, from Darcy Mitchem's When Lightning Strikes (2004), p. 219:

They traveled in silence, until the rumble of ice made them turn to assess the danger from above again. With a palatable relief they reached the far side, where they found the narrow trail that switchbacked up the head of the valley at Whatcom pass.

Here, I don't think there's any way to rationalize palatable. I blame the editors, who exist precisely to save writers from such embarrassments.