Linux kernel 3.9 brings numerous breathtaking features, among which we can mention improved support for F2FS (Flash Friendly File-System), improved ARM support, new drivers, which bring support for more hardware, and much more.
"Anyway. Whatever the reason, this week has been very quiet, which makes me much more comfortable doing the final 3.9 release, so I guess the last -rc8 ended up working. Because not only aren't there very many commits here, even the ones that made it really are tiny and not pretty obscure and not very interesting."
"Also, this obviously means that the merge window is open. I won't be merging anything today, but if you start sending me your pull requests (Konrad already sent in his Xen pull request for the 3.10 merge window a week ago), tomorrow the flood gates start opening," Linus Torvalds said in the official announcement.
Highlights of Linux Kernel 3.9:
• Improved support for the F2FS (Flash Friendly File-System) filesystem for Samsung developers;
• Improved ARM support;
• Zero-Power Optical device driver;
• Audio/sound improvements;
• Initial support for AMD Radeon HD 8000 series;
• Synopsys ARC700 CPU support;
• Improved ARM SoC support;
• Improved power management;
• Faster LZO compression;
• Experimental RAID5/6 support for the Btrfs filesystem;
• Fixes EXT4 corruption bug;
• Google's Goldfish.
Last but not least, Linux kernel 3.9 also comes with several small, but important improvements for the other supported filesystems, as well as networking, virtualization, security, crypto, perf and block areas.
For a comprehensive list of all the newly added drivers, as well as newly supported devices and overall improvements, do not hesitate to view the Linux kernel 3.9 DriverArch page and the official changelog.