Personally, I don't have much of an opinion on either side of this case, but I'm fascinated by the attention it's received.
A few years back, there was a concert being held in NYC featuring the Beastie Boys and RATM. It was announced at some point that the bands were going to donate the proceeds from this concert to the Free Mumia fund, but weren't officially calling it a "benefit concert".
About 75% of the tickets were returned to the box office.
The one thing I heard out of that whole uproar that made perfect sense to me was something said by RATM's guitarist during a radio interview.
He said (paraphrasing), "I don't care whether you agree or disagree with me. The important thing is that each individual form their own opinion based on the facts of the case. Don't agree with me just because I'm a famous person. Don't agree with me because it's the trendy thing to do. Get out there, do your own research from a variety of sources, and form your own opinion. Then, whether you agree with me or not, I'll respect your opinion."
While I've never felt particularly compelled to follow up on that advice for this particular issue, I have great respect for someone who is intellegent enough to publicly say what so many people in our society ignore.