I think it's more what HN specifically pays attention to, than what gets attention in a global sense. My read is that the community here is focused on web-oriented, low-capital, low-time-to-MVP markets (Y Combinator's preferences sort of set the tone, but lots of bootstrappers have similar aims). That tends to make higher-capital, higher-time-to-market, high-R&D or high-sales-touch, slower-growth businesses a bit off the radar here.
I think partly it's that people are inspired by the category of businesses that seem like: given $30k and two years in a garage, I could do that! This requires a particular kind of company, and lots of success stories just don't seem like the kind of thing you could do in a garage, so they aren't part of this particular corner of the Valley mythos. For example, one of the top tech IPOs of 2013 is CDW, a Chicago-based B2B firm that's been slowly growing since 1984 by building partnerships and logistics infrastructure, and is now IPO'ing 29 years later. Totally different kind of company.
I think the location actually matters a bit less. People probably do pay more attention to SF-based companies just because that's where a lot of the startup-sector media is, but companies from elsewhere that fit the model I described also get press, like 37signals (Chicago) or SoundCloud (Berlin). A number of the more prominent HN posters with startups are also from outside the Valley, like tptacek (Chicago) and cperciva (Vancouver).