I think we really need to clearly define our definition of "jump the shark" here, because I think that means different things to different people. (Of course, this entire conversation is governed by the "it's all a matter of taste" rule.)

For one, I think using landmark recordings like "The Joshua Tree" in this context can be a bit unfair. We're talking about an album that almost any knowledgable fan of rock music has on their top 10 or 20 of all time. Of course there's going to be a letdown from The Joshua Tree to *anything*. And maybe you legitimately don't like anything U2's done since then, that's fine. But holding a band up to the standard of a once-in-a-lifetime recording and concluding they've jumped the shark seems wrong to me. Pink Floyd, by most peoples' accounts, never made an album better than Dark Side of The Moon, but they released a lot of good albums afterwards, some that came pretty close (again, if you measured the opinions of a representative sampling of the population.)

So, if you mean that U2 has put out nothing good since The Joshua Tree, you're entitled to your opinion, and that's cool. But I think the better way to measure "shark jumping" is to compare what they've done to the average of their material prior, and evaluate whether the graph slopes upward, downward, or stays the same.

Secondly, I think a band is entitled to a clunker or two before one can pronounce them dead. I'm sure that any band prolific enough to even be talked about in the "jump the shark" conversation has had at least one record they (or their fans) would like to forget about. I think for a band to have jumped the shark, they have to have had consistently sub-par output since the moment that's being cited.

Now, maybe even with these definitions, you will stand by your Joshua Tree suggestion, but I just wanted to make sure we're all speaking the same language here. I personally think that, while Achtung Baby was a step or two down from The Joshua Tree, it's still a fantastic album that stands up well amongst U2's library. Zooropa was maybe one more step down from Achtung Baby, and Pop was probably several steps down from that. But, as Bitt says, All That You Can't Behind is by most informed accounts a good album, and that would seem to invalidate the "jump the shark" theory. I conclude that U2 hasn't jumped the shark yet.

For a good musical jump the shark example, I'll submit Metallica as Exhibit B. Their self-titled record was clearly the moment of shark-jumping. There might be some who'd go back further and say "The Black Album" was also crap, and probably others who'd say they never made anything good to begin with. But I think if you look at the average fan's opinion, it was a solid release, and most everything since has sucked. That, in my mind, is jumping the shark.