Reasons why such an idea would be helpful to both sports:
Benefits to the NHL:
MMA is exploding. Particularly the UFC brand. Not only would it help get the NHL get more exposure in the US (particularly non-hockey markets), but the inroads the sport has made into other non-hockey markets, Japan, Brazil, the UK, Australia, etc... could all prove to be a major growth opportunity for the NHL. It would provide instant access to sports fans who have an appetite for fast-paced, physical sports, and can accept a measure of violence within a strict framework of rules. Further, their presence in Vegas may be an asset in exploring a potential All-Star Game location, possible expansion, etc. The UFC is one of the most innovative of all sports in their marketing and promotional techniques. They're experts at appeling to the 18-35 male demographic, especially.
Benefits to the UFC:
Hockey fans have already demonstrated a tolerance for, and at times even an appreciation for, an element of violence in sport. Certainly a pre-requisite for becoming an MMA fan. Further, the NHL has managed to overcome much of the mainstream misunderstandings of their sport. They have presented themselves in a way that better represents the sense of competion, while not sensationalizing the violent aspect. They have a strong presence in Sweden, Finland, Russia, the Czech Republic, Slovakia, Norway, etc.
The reason why Canada is the heartland of hockey, and the mecca of MMA, is no coincidence.
As many have already pointed out, this thread is a sobering reminder of how completely uninformed the mainstream is when it comes to MMA. No wonder it still isn't being sanctioned in NY state. The UFC doesn't do itself any credit to shed this image either, with all the terrible nu-metal, blood spatter graphics, checker plated steel, the "cage", "fight wear", etc. Sponsors like Harley Davidson. All it does is attract alpha d-bags that want to see someone bleed. And those turds already know all about the UFC.
Anyhow, I digress.
To those MMA naysayers out there, keep in mind that hockey allows bare knuckle fighting, and there are no weight classes. Look at the issues with head shots and the number of concussions in the sport. Jesus, skiing is more dangerous than MMA.
For the supporters of of MMA, know that HF has a great board dedicated to the sport on 'Page 2'. It seems a lot of the members here are unaware of it. You can find it here:
http://hfboards.com/forumdisplay.php?f=234