I tried creating a new company by posting the following to Highrise and it appears to ignore the web-addresses. Is this not supported through the API?

body = " 
    <company>
      <name>#{company[:name]}</name>
      <background>#{company[:description]}</background>
      <contact-data>
        <web-addresses>
          <web-address>
            <id type=\"integer\">1</id>
            <location>Work</location>
            <url>#{company[:url]}</url>
          </web-address>
        </web-addresses>
      </contact-data>
    </company>
" 

I did a search in the forums because I was having troubles setting this as well. It turns out there is an error in the API documentation. I was using
<address>http://mysite.com</address>

when in fact it should be

<url>http://mysite.com</url>

I see you are already using <url> so I’m not sure what your issue is, but hopefully this post will help someone in the future.