So, sure, it's all great to hear when you see this sort of stuff splashed across the internet, but it's always best to go right to the source to see just what's going on right this second. When asked about the third installment in London, Murray waved it off and basically said that his participation depends solely on a script he hasn't seen nor read yet. The actor also spoke a little about sequels in general, saying (in so many words) that Ghostbusters II was definitely not as good as the first one, which is one reason why he's so hesitant to give it another go.
Says Murray: "I'll believe it when I see it. I saw a guy talking about the end of the world a couple years ago, and I still haven't seen that either -- so I'm not going to believe the Ghostbusters story until I see it."
Watch the Bill Murray/Ghostbusters 3 interview over at SciFi Squad