I don't really know of any spaces like that (and as a CS PhD student I would enjoy something like HN for grad students), but just to latch onto this general post -- does anyone have links to good Hacker-News-like sites for various topics? There's a lot I like about HN but the whole startup scene and "yet-another-web-framework.js" is less relevant to me.
You'll probably like Lambda The Ultimate. It's a Programming Languages weblog with discussions and forums, but their traffic and updates are miniscule in comparison to news.ycombinator. If you're a busy PhD student, that's probably not a bad thing.
This site has a lot of promise: http://www.datatau.com/ Unfortunately, the community is not yet large enough or active enough to have a ton of new posts everyday. That said, there are many quality links
