Allow me to do my best imitation of David Thorpe and present these "Beefs in Brief"...
Jay v. Jeff: Per the Chicago Tribune, Jay Bennett is suing Jeff Tweedy for back royalties from Wilco, saying, among other things, that Bennett was not compensated for his appearance in I Am Trying To Break Your Heart. I admit I don't know much about the business of film, but shouldn't Bennett be taking that up with the film's producers?
Wayne v. Win: A while back, Wayne Coyne said some unflattering things about the Arcade Fire's Win Butler in an interview with Rolling Stone. A few months later, Coyne is both apologizing and backtracking in an interview with Entertainment Weekly. Coyne seems like a nice guy, but I'll let others determine whether or not his after-the-fact clarification actually tracks with what Rolling Stone quotes him as saying.
Cat v. Chris: Yusuf Islam, who used to be known as Cat Stevens, has said that Coldplay's "Viva La Vida" is actually not a ripoff of some Joe Satriani song at all, because it's actually a ripoff of his song "Peace Train" [listen here]. He's not suing, though, as of now. You'll recall that previously he made a deal to split royalties with the Flaming Lips over "Fight Test," which they even admitted bore a strong resemblance to his song "Father and Son." I'd say it's more that "Viva La Vida" is such a generic song (though not a totally unpleasant one) that you can find similarities to about a thousand different songs if you listen hard enough.