I've been writing about 301'ing pages off my Pandalized sites as an experiment in another thread. Today I got a message in my WebMaster Tools account saying:
The URL www.pandalized.com/page.html is no longer appearing in Google search results because our algorithms have selected www.freshsite.com/page.html instead. Please see this Help Center article for more information about this message.
So I went back and checked my 301's with LiveHttp headers again, and as long as I invoke Private Browsing to turn off cache and all that, I get back 301's every time.