Jedberg last year stating that a startup buying physical machines today is foolish: http://www.reddit.com/r/IAmA/comments/a2zte/i_run_reddits_se...
It seems like that would make a lot more sense for Reddit, since I/O is so slow and flakey on EC2 (from what I hear), and it's not like they're really taking full advantage of the elasticity that EC2 provides (by massively scaling up and down to fit major load variance)