I don't have a lot of links for April because I was pretty busy getting married 😛
Nevertheless, here are some links to stuff I had time to check out:

Graphics

Some interesting research to be published at Eurographics 2013 on automatically creating locomotion controllers for biped, triped, or quadruped animals can be found in the paper titled Animal Locomotion Controllers from Scratch by Kevin Wampler, Jovan Popovic, and Zoran Popovic.

RenderingPipeline.com has a great post with lots of links to Low-Level GPU Documentation. Useful stuff for any graphics engineer.

The Distant Souls development blog has another good write-up of the remaining GCN performance tips posted by Nick Thibieroz on Twitter.

Ke-Sen Huang's page of SIGGRAPH 2013 papers has gotten quite full in the last few weeks. Lots of interesting new papers to read.

Other

Niklas Frykholm gave a talk at GDC 2013 on how to work collaboratively on creating assets for a game. The main takeaway is that you should have a simple asset format that gives each object a GUID and stores simple key-value properties so that these asset files can be auto-merged via a semantic merge tool that understands the format. It's a great idea and I've worked on engines that did exactly what he proposes. I really wish the Unity engine would do this better with its text-based asset format. It would be nice if there was a semantic merge tool available for it.