I was actually surprised that A Deepness in the Sky didn't make it to the list when A Fire Upon the Deep did. Deepness had a lot of themes that satisfy hacker tastes (not just in terms of the technology but also the socio-political ramifications of it).

I had first heard of it when DanielBMarkham highly praised it (http://www.hn-books.com/Books/A-Deepness-In-The-Sky.htm, HN discussion here at http://news.ycombinator.com/item?id=2170579) and it's definitely one of the best sci-fi books I've read in years.