It's a great idea - is there any word as to whether it's patented/patentable, or might we see this on other OSes?
"App Nap" is a familiar concept to anyone who has ever played a game with unfocused framerate caps (like most MMOs, for example). It being enforced by the OS may be new, though. It kind of feels like a more aggressive `nice` though.
AFAIK zram is using LZO compression. According to some tests it is about the same efficiency as WKdm (used in Mavericks) but it has bit slower compression speed [1].
zram is an experimental kernel module since 3.2 and can be installed: [2], [3], [4].
[1] WKdm vs LZO http://terpconnect.umd.edu/~barua/matt-compress-tr.pdf
[2] Gentoo zram http://wiki.gentoo.org/wiki/Zram
[3] Arch zram https://wiki.archlinux.org/index.php/Maximizing_Performance
[4] Debian&Ubuntu zram http://gionn.net/2012/03/11/zram-on-debian-ubuntu-for-memory...
I was going to say that this is crazy: why waste RAM to hold swap space, when you could use that RAM to avoid swapping in the first place. I still think it'd be odd to reserve a significant chunk of your memory for it. But I can see how it'd be pretty cool if you can manage it dynamically, ie. only start compressing memory as you run out of it to avoid hitting the disk.
Of course the usual rule still applies: if your PC swaps often, get more RAM; or if the RAM is not upgradable, go back in time and buy a machine with more RAM, then smack yourself on the head for not doing so in the first place. :)
Because you can get faster performance, and more importantly lower energy usage, on the same hardware.
Note that you need kmod–staging from RPMFusion.