Reddit is very large: there are almost certainly subreddits for that sort of stuff. As an example, /r/Haskell[1] is fairly technical (it is frequented by people such as dons[2] and gwern[3], and presumably they would've moved on from r/haskell if it became overly banal).
(Also, a brief googling turns up /r/startups[4], but I've got no idea of its standard of discourse.)
(Also, a brief googling turns up /r/startups[4], but I've got no idea of its standard of discourse.)
[1]: http://www.reddit.com/r/haskell [2]: http://donsbot.wordpress.com/ [3]: http://www.gwern.net/ [3]: http://www.reddit.com/r/startups