Comment by whalesalad

There's a kabillion factors to consider though. With that many users, yes the exact implementation matters less and the ancillary systems and how they interact are more critical. But, building the platform, being able to iterate quickly and deliver robust functionality along the way is important as well. Not that Ruby hasn't, but Django and Python have really proved their worth with some of the heavy hitters recently. Instagram, Pinterest, FriendFeed, Disqus... It's an impressive roster.