When an open source project is really working, things can move frighteningly fast. One developer can focus on a feature while others are reviewing the code and preparing it for merge, allowing things to move forward in a very streamlined fashion. This not only gets things done faster, but each coder can specialize in what they do best, producing the best possible product for the user base.
When things come together just right, months like this can happen. The June Progress Report is a massive monument to months of hard work put together by not one, but all of the people contributing to the project.