Intel SNA was introduced in mid-2011 as a new 2D acceleration architecture for the xf86-video-intel X.Org driver. While the name implies the "Sandy Bridge" generation of hardware, SNA back-ends are available for newer and older Intel graphics cores too. SNA is largely the work of Chris Wilson at Intel's Open-Source Technology Center and over the years he's tuned this acceleration method to be much faster than UXA, the current stock Intel DDX acceleration path.
Intel SNA is very fast and is an improvement even for older generations of Intel hardware. With the modern Intel Linux graphics driver, SNA is generally bug-free and a noticeable improvement over UXA. While SNA is a huge advantage for Intel Linux customers, it's not the default but at least last year it was made easier to use.
For the past few years there has been a desire by Ubuntu Linux developers to enable Intel SNA for Ubuntu, but in the end it hasn't happened. For the Ubuntu 13.04 cycle, this acceleration change is again being considered.
Canonical's Bryce Harrington wrote in a new mailing list message:
SNA has been under very active development the past couple years. We've been monitoring (and testing) this development, and providing it as an opt-in option for users who wish to use it. We evaluated enabling it last cycle but were not certain about its stability across a wide breadth of card models.In terms of the late X.Org updates for Ubuntu 13.04:
We likely will try again this cycle. We are planning on an X.org stack update rather late in the cycle, and if we include SNA we believe it will be most stable with that stack; thus the lack of attention we've given it right now - any testing we do now would have to be redone with the newer code anyway.
If you want to help, one thing you can do right now is to install the xorg-edgers PPA, enable SNA, and report any SNA-specific bugs you find to upstream.
Mesa 9.1/10.0 (whichever it ends up being called), xserver 1.14 (nothing dramatic happened there), and the usual driver updates.
"late" might also mean "for alpha2", we haven't decided yet.