Has apparently been found. It seems that archeologists had been looking on the wrong island all along. Instead of being on modern Ithaca, they now place the tomb on an entirely different, but neighboring island, Kefalonia.
Archeologically, I have no idea how to rate these claims, but according to some of the background in the linked article, Kefalonia seems more logistically suitable as the site of a major Mycenaean city. Even the ancient Greeks needed water last I checked.
Archeologists were silent on whether they found a tomb full of 50 suitors.
NP: "Look Here" - The Clash