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You can almost always discern where JavaScript is in a page because it falls between <script type="text/javascript"> and </script> tags.
The call, through the onchange event handler, doesn't appear to do much. It seems to simply direct the browser to focus on the form object it's already focused on.
onchange="go(this)"
I think you missed this bit, Rambo - it's powered by javascript.
As for the search engines (I assume that's what you mean by readable), I wouldn't count on the fact that they can follow these links, which are not standard href links. I would strongly recommend duplicating them with standard links, either in a footer or on a site map page.
Dropdown lists are a bad idea as primary navigation from a usability point of view, although they are useful as a secondary way to jump between sections of a site. Your site should be fully navigable when javascript is disabled.