A DigitalPoint Forums thread reports that MSN Search (aka Live.com) is indexing permanent 301 redirects. What this means is that if you search on a term or command that triggers the domain that is 301ed to show up, it will show something like the following in the search results.
The document has moved here. Apache/2.2.0 (Fedora) Server at www.xxxxxxxxxxxxxxx.com Port 80
Some members have confirmed this to be true, but I personally tested serveral domains that I know are 301 redirected and was not able to reproduce it.
I am thinking it may be about the server type, the configuration and so on. But also, related to how Live.com handles those server responses.
Forum discussion at DigitalPoint Forums.