In Dashboard... General... Settings, WordPress uses the description "Site Address (URL)" to mean what I think is elsewhere referred to as home.
Http://codex.wordpress.org/Changing_The_Site_URL has exactly the opposite.
In particular, the function site_url() doesn't resolve to the "Site Address (URL)" as indicated on the dashboard, it gives what is called the "WordPress Address (URL)". This caused me some confusion as I was chasing down what I thought was a different but related problem.
I think it would be helpful to clarify/correct the descriptions on the dashboard to match the functionality of WordPress.