Linus released the RC kernel on a Saturday rather than Sunday due to his travel plans tomorrow around the Linux Foundation events in Chicago next week. He's also hoping/enforcing that all subsystem maintainers landed their merge window changes in time.
Linus wrote in the announcement, "this merge window was slightly smaller than the last few ones, probably due to summer slowdowns in the northern hemisphere. Which is not to say that it was *small* - the last few releases have been larger than usual, this one is just fairly average. It's certainly big enough that I can't post the shortlog, so as usual this just appends the "mergelog" where the people credited are the people I pulled from, not necessarily the people who wrote the code."
For those unfamiliar with the many Linux 3.17 features and other changes, there's our dozens of Linux 3.17 articles to date plus an overview of the new features as of last weekend but I'll have a new article out shortly covering all of the features as there was still some notable work that landed this past week.