Not this Lieberman, this Lieberman. It's not a disaster for the reasons some people think; I know Avigdor Lieberman a little bit, and he's actually a person interested in a cold compromise with the Palestinians. It's a disaster because he's made himself into a racist. The language he uses to describe Israeli Arabs is despicable, and self-destructive, because the key to Israel's future (well, one key at least) is the total enfranchisement of Israel's Arab minority, not its disenfranchisement. Maybe it's just a dream, but an Arab population that has the same rights, freedoms, opportunities -- and responsibilities (i.e. national service of some sort) as the Jewish population is an Arab population that is too busy and successful to hate. (Yes, I know Israeli Arabs have the same legal rights as Israeli Jews, but what I'm talking more about opportunities here).
Another rather important reason Lieberman's appointment is so reckless: This is the man who is going to be Israel's public face. The appointment is a gift to those who believe that Israel is nothing more than South Africa on the Med. Especially at a time when Israel's international reputation has never been lower, how could this come to pass? The answer, of course, is no secret: Israel's dysfunctional politics are largely to blame. In the American system, a person like Lieberman would be marginalized. In the Israeli system, the Liebermans rise to the inner cabinet. This is also, I must say, Tzipi Livni's fault. She could have joined a unity government and kept her job as foreign minister. But that would have been in the best interests of the State of Israel, rather than the Kadima Party, so her decision is, in retrospect, obvious.
Israel is serious about a great many things, but governance isn't one of them.