All-in-One Scrolling Page: Good or Bad for SEO?

I typically code multiple pages for my clients - things like index.html, about.html, services.html, contact.html, etc., each with appropriate and relevant <title> tags. But “one-pager” sites are becoming popular and I’m wondering if they’re good or bad as far as SEO is concerned. What I’m talking about is a web site where everything is in a single file, and the navigation uses anchor links (for example, “About Us” might point to “<div id=“about”>…”) Some of these sites use jQuery to do smooth scrolling effects. While sites like this can be visually attractive and faster to navigate (once you’ve downloaded the page the first time), does the lack of separate files and/or <title> tags hurt SEO?