There's a hazy line, but it gratifies my intellectual curiosity (as someone who is relatively ignorant of the subject) so I submitted it.
From: http://ycombinator.com/newsguidelines.html
What to Submit: Anything that good hackers would find interesting. That includes more than hacking and startups. If you had to reduce it to a sentence, the answer might be: anything that gratifies one's intellectual curiosity.