Linux creator Linus Torvalds last night announced the release of version 3.9 of the kernel. Available for download at kernel.org, Linux 3.9 brings a long list of improvements to storage, networking, file systems, drivers, virtualization, and power management.
H-Online editor Thorsten Leemhuis has an excellent rundown of what's new in Linux 3.9. One new feature, listed as "experimental," allows SSDs to act as caches for other storage devices. "This feature is able to speed up data writes, as it allows the faster SSD to first cache data and then, in a quiet moment, transfer it to the slower hard drive," Leemhuis wrote.