It isn't happening that much. National Review is ridiculing it.
But it seems it is getting a little traction. WND, has an article where one of there writers interviews Michael Hill, president of the League of the South. The link is here:
http://www.wnd.com/2012/11/spanish-vote-endorses-secession-parties/
It could be argued that having WND pick up your cause doesn't represent mainstreaming very much, but rather your fringe status.
Town hall had another neo-Confederate, Bill Murchison, former writer for Southern Partisan, give his take on secession. You can read the article here:
http://townhall.com/columnists/billmurchison/2012/11/27/thoughts_on_secession/page/full/
There is this article at the Human Events web page which argues for a political program to avoid the threat of secession. http://www.humanevents.com/2012/11/26/the-spanish-secession/. The author isn't advocating secession but finds it a useful threat.
I am not seeing the radical right pick up much on secession so far. email me links if you know of sources I over looks.
I think at this point not much will happen until Obama responds.