I don't know why you got so many down votes. Maybe HN folks got too sick of armchair architects/hackers. Honestly, what your said somehow resonated my inside hacker. I think lots of hackers share similar opinion --- as hardware/network are getting so much cheaper nowadays, it may be very feasible to build and operate "web-scale" apps like Twitter and Reddit with small but capable man powers. Lots of people here agree that the main problem is less of a technical one, but more of a business one --- how to jump start a community in an area especially with a seemingly winning market leader over there. Perhaps, there are still opportunities in the area. Maybe Twitter will be the next Google or maybe not.

Back to the topic, three months ago someone went ahead and pulled off a high-performance (no sure its scalability) Twitter clone in C. I recalled it's a good discussion on such a topic.

Discussion can be found on Reddit: http://www.reddit.com/comments/f16mw/ive_never_been_impresse...

Its website is at http://blerg.dominionofawesome.com/