There is actually 2 meetups I know of. The Boulder poly meetup (every week) is mainly younger folks dealing also with GLBT issues, (but is loaded with drama right now). The Denver poly meetup (monthly and is this week) is full of older adults and professionals that are more experienced in making long term poly relationships work. Both are pretty useful in their own way, and are quite different.
"[Polyamory] is not all wine, chocolates, and fucking..." horribly paraphrased from RedPepper