A thread at Cre8asite Forums discusses the effects of doing search engine optimization of one page websites.
One member says, "Is it more of a benefit to having one page whereby you are scrunching all of your content, and subsequently, your keywords onto one page?
The nice thing is that when you do link building campaigns and directory submissions, you don't have to focus on multiple urls. Instead, you just use one url and switch it around with various anchor text." But some comments talk about the limitations.
Ammon posts some thoughts on the subject:
A one-page website always has less options than a multi-page website. That always means it has limitations, and is slightly handicapped (possibly a lot more than just slightly). Your own internal links and link text (navigation) have weight in many search algorithms. Your site structure can have weight. With a one-page site there are neither internal links, nor structure. Whatever you can do to make one page successful, you could do to six pages to make the site more than six times as successful.