Room: Ballroom C+D
Postgres has for a long time been lauded to handle concurrency well, being able to process more requests if additional resources (CPUs) are added. Unfortunately, after that had been determined many years ago, for a while not much further work had been put into the topic. But since then the number of cores and the general architecture of parallel systems have changed leading to a number of scalability problems. In the last few years a number of people worked hard on fixing these.
I'll talk about some of the major recent scalability improvements (9.2, 9.5, 9.6) that have improved postgres' scalability massively and what the biggest remaining scalability concerns are. Some of the remaining issues can mainly be addressed by changing Postgres, others can be worked around on the application side.