Regarding tweet distribution, I was one of the folks who built the first scalable solution to this problem at Twitter (called Haplocheirus). We used the Yahoo “

Regarding tweet distribution, I was one of the folks who built the first scalable solution to this problem at Twitter (called Haplocheirus). We used the Yahoo “Feeding Frenzy” design, pushing tweets through a Redis-backed caching layer. Feel free to continue using that (historically-correct) answer in interviews. :P