The Debian development has decided that Debian 8 "Jessie" will be powered by Linux Kernel 3.16, which is scheduled for release very soon.Debian has a long development cycle and that means that it's hard for the developers to actually track and implement a particular Linux kernel. Some talks about adopting Linux kernel 3.16 took place back in May and it looks like the devs have finally settled on this release.
Linus Torvalds usually sticks to a general schedule when it comes to new kernel releases, but things can go wrong and the launch window can be missed by a week or two. The development cycle for the 3.16 branch of the kernel is getting closer to the end, and last we heard about it, Linus was hoping to make the final announcement this week.
"The Debian Linux kernel team has discussed and chosen the kernel version to use as a basis for Debian 8 'jessie'. This will be Linux 3.16, due to be released in early August. Release candidates for Linux 3.16 are already packaged and available in the experimental suite."
"If you maintain a package that is closely bound to the kernel version - a kernel module or a userland application that depends on an unstable API - please ensure that it is compatible with Linux 3.16 prior to the freeze date (5th November, 2014). Incompatible packages are very likely to be removed from testing and not included in 'jessie'," say the devs on the official website.
There is one major problem when you try to determine what kernel version you will integrate in your system. It's difficult to anticipate if a kernel will be adopted as an LTS release, and that is very important when you also consider making your OS an LTS version.
If Debian 8 becomes a long term support release and the Linux kernel the devs have adopted reaches EOL status (end of life), they are left with two choices. Either adopt the kernel themselves and continue to implement updates (the way Canonical is doing right now with Ubuntu 14.04 LTS and Linux Kernel 3.13) or adopt a new kernel. Changing the kernel midway through the cycle is difficult and it's not recommended.
The release date for Debian 8.0 "Jessie" hasn't been determined yet, but the final freeze for the operating system will be in place on November 5, 2014. It's unclear whether they might decide to change it before then or if the decision is final.