i'm for hypens... SEO understands better your keywords when they are separated. almoust all my 2 word domains contain hyphens. i've just bought now one named akon-mp3.com
there is a myth that hyphen domains have a lower resale value, to some users yes they do to others they are the same if not better. i have sold many sites that contain hyphens for thousands more than sites i have had with out the hyphens. search engines see a hyphen as a space so if your domain is cheapwholesalegoods.com how many people do you know of that search for cheapwholesalegoods none that i know of most search like "cheap wholesale goods" so the domain name cheap-wholesale-goods.com will have a higher ranking but thats the extreme i limit my domains to one hyphen if possible. of course off line advertising would likly not work so well for a domain like that. but how many of us do off line advertising as a major part of advertising?
From a consumer standpoint, I personally don't like hyphens. As far as if it helps or not for SEO is another matter entirely. At the end of the day though, you will be wanting people to come to your site, so do whatever you think will achieve that end.
in French, hyphens are more or less accepted by domainers. At least, there are very appreciated by webmasters
When it comes to hypen domains it's simple: 1. register both versions of the domain (some-domain.com & somedomain.com) 2. do a 301 redirect on the hypen domain (some-domain.com) to the nonhypen (somedomain.com) (that way both the users and search engine spiders are happy)