Say you have a website which has been penalised not for its content but for what Google sees as 'unnatural links' pointing to it. You've gone your best to clean things up but the problem is just too overwhelming and it might make sense to start with a clean slate.
Assuming the content itself is excellent and it's only the link profile that is problematic can you shift this content onto a new domain?
Google has an article about moving an entire site from their index which suggests you should robot the content and then use the URL removal tool in WMT to remove the site. Having done this, what happens when this content appears on a new domain? What if there is a lot of content (say a few hundred pages) and some of it dates back a couple of years?