christopher,
You can get the subdomain from the request object in the context of a
controller (or a view) like this:
<%= image_tag logos/#{request.subdomains.first}.gif %>
What is @site ? Do you define it somewhere? If so then you can assign
the subdomain in your controller like this, provided @site is a hash,
or an object with a subdomain attribute.
@site.subdomain = request.subdomains.first
I would suggest in application.rb, so that it is available to all
your controllers.
-christos
