According to Matt Cutts of Google, there are no limits to the number of 301 redirects you can use when moving a site.  Chaining 301 redirects, however, is another story.  Towards the beginning of the video Matt mentions that over at the Google Webmaster Help Channel they have produced over 375 videos to answer questions from Webmasters.  Matt says it’s now time to go back to the beginning and “do a little more tutorial, sort of informative videos to sort of, you know, make sure that the people understand all of the really important things that matter, but that are also sometimes a little more basic…”   So if you are a newbie webmaster, or just want to review the basics, keep your eye on the Webmaster Help Channel.