In the video, Matt Cutts and Rand discuss headers, status codes, how much of the web is worth indexing, porn, redirect chains, URL structures, geo targeting, leaking link juice, and amateur beekeeping!:
"Is It a Bad Idea to Chain Redirects (e.g. 301-->301-->301)? "It is, yeah."
Matt was very clear that Google can and usually will deal with one or two redirects in a series, but three's pushing it and anything beyond that probably won't be followed. He also reiterated that 302s should only be used for temporary redirects...but you already knew that, right?"