n00b1 - 10:08 am on Sep 28, 2012 (gmt 0)
It definitely returns '410 Gone' according to any header check I run.
It could be that the original URLs weren't properly removed from the index and Google has sort of redirected automatically. The number of 'via this intermediate link' instances and just the rankings of certain pages seems to indicate this might be what has happened.
I am running a little test at the moment. I have the 410 returned on all 'www' pages. I have requested removal of a specific page from the www version (it isn't displaying in the search results of course - only non www pages are). Strangely this has caused the non-www version to drop from the index. What's up with that? It is like no matter what I do it is viewing them as one and the same... Although the list of URLs removed in this tool is unique for both the 'www' and 'non-www'.