Don't listen to the "one-word wonder" above. It's better than most people would imagine!
Tim Kelly and the Las Vegas Track Club are an organization of about 800 people who are extremely active in the local running community...
http://www.lvtc.org/
Also, Dan Campbell and his Las Vegas Running Team are a no-fee organization that also organizes many races in the Clark County area. Every Sunday morning he provides free "crew" support during your weekly long runs in his van...
http://www.lasvegasrunningteam.com/
The climate isn't exactly like Oregon or Southern California, but it's not nearly as bad as the scorching urban legend that others would perpetuate. One of the athletes that I coach is a 26-year-old young lady who lives there. She started running less than two years ago, but thanks to her own dedication and the support of organizations like those described above, she qualified for Boston two months ago!
There are also trail run opportunities in the foothills. Check out the message boards at those two web pages above...they can tell you quite a bit more.
I would say go for it!