There is a lot of confusion about the use of hyphens being used in domain names.  While researching hyphenated domain names I found a lot of conflicting information  so I will give you a distilled view of what is currently believed to be the facts  regarding hyphens in domains.

When I started had a lot of trouble finding a domain that I could use to reflect  the topic of my site. It used to be the case that using a hyphen to separate keywords  in your domain name would give you a better ranking in the search engines. For a while this was the case but due to the over zealous use of keywords in domain names,
search engines now consider this as a spam technique.

If you use an un hyphenated domain name like myself using keywords it is generally  believed that search engines such as Google can pick out the keywords. The answer  is undoubtedly anchor link benefits and ease of readability. If you have hyphens in your domain name it is easier for a human to read and recognize the keywords
in a domain.

Recognizing the domain name is one thing but entering a domain name into your browser  is another. It is easier for someone to type the un hyphenated domain name and it  is easier for someone to give out the domain name to a customer if it doesn’t have  hyphens in it. If a webmaster links back to your site from their site they often  use the domain name as the anchor text. I do use hyphens but only in my file names  as this makes it easier for people to read and people are less likely to type in a page name as they are a domain name.