The CU9 release for AX2012 R3 was released last week. Here are a few links to some articles to read up more. The Lifecycle Services download and updater is here as well as a download for the slipstream update. If you are doing a new install of AX2012 R3 you probably want to build yourself a slipstream DVD and use that for all your installs.
Lifecycle Services update page.
There is a TechNet article of the new features that you might want to take a look at if you are already on CU8 to see if there are some new capabilities you can take advantage of in your project.
The partnersource/customersource page is available here for more information as well.