Well that doesn't make any sense. Kazaa standard version is available free from Kazaa on Kazaa's website. Now, if Metallica posted mp3's available on Metallica's website free for download directly from them, you might have some kind of analogy. Just because songs are available "somewhere" free for download doesn't make that the same as the rightful owner making it free for download.
If you can't see that difference, there's no hope for you ever seeing music piracy as wrong.
I'd like to know what it is that makes their version/use of Kazaa "unauthorized," whether that is from using Kazaa lite, modifying the software, or something else. I agree, this is certainly going to be an interesting legal case, assuming Kazaa has a legitimate claim. It won't make any of the music piraters any less guilty of breaking the law, but it might make the evidence the RIAA has gathered thus far inadmissable in court.