I'd say that the closest the US got to having "a demoparty like this" (meaning: with such good releases and turnout) was NVScene in 2008 which I helped organize. The event was documented in this now-severely-outdated blog, if you're interested in catching up: http://demotrip.blogspot.com/
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"The laptop itself uses an 366 MHz AMD x86 processor and it 128 MB RAM (though, some models have 256) and a 512 flash memory. It does not have any hard drives — actually, there are very few moving parts on it at all, but more about that later. Red hat is making the Linux-based operating system for it, but in theory you should be able to install any distro that you want on it. It is also equipped with wifi and USB ports so that children can use electronic school books. It is also able to surf the web and do e-mails. The laptop is also equipped with a web-cam, and after Håkon demonstrated it to us, it turned out to be of decent quality as well.""
Getting nowhere with Geffen, the demoscene has now risen to he aid of Tempest, first by creating a stirr at SomethingAwful (files downloadable from the forum), and later at the news-site Digg.com as well as on YouTube, with a video demonstrating the blatant rippoff.
Being an online-posting musician myself — what rights do I have if this should ever happen to me, and what can be done to raise awareness about such things?"