> I imagine that news.ycombinator.com is a more common Referer than news.google.com in the development community

I wouldn't be so sure of that; considering my own pattern, even when my reading is being driven by HN, I usually do several google searches for related content, including frequently Google News searches for related news items from other sources, for each page I go to directly from HN. And not all of my reading -- even related to development/startup things -- is driven by HN.