Linus was debating whether or not to release Linux 3.15 final this weekend or not, but due to having last-minute fixes, Torvalds is being cautious and decided to release 3.15-rc8. Linus notes, "And it's not like I think rc8 is in any way broken. I just don't feel comfortable doing a real 3.15 release without a _bit_ more time for people to use the fixed dentry code."
While normally the merge window for the next Linux kernel cycle doesn't open until after the current kernel has been officially christened, Linus this time is opening up the merge window for Linux 3.16 right now. Linus will be traveling on a family holiday in two weeks, so he's decided to open the merge window now rather than delaying the Linux 3.16 merge window, do it while traveling, or making other modifications to the kernel schedule. Linus will see how it works with the week-overlap of the merge window while finishing the Linux 3.15 kernel baking to see if this change in process will persist for future releases.
Linux 3.15 has a ton of new features while already we have been looking at features coming to Linux 3.16 for its release later in the summer. The 3.15-rc8 announcement can be read at lkml.iu.edu.