No public change-log has yet to be published for this most recent beta, but it's expected that the driver can handle the brand new AMD Radeon R9 290X and R9 290 graphics cards. Other changes -- if any -- are not known at this time.
The first Catalyst 13.11 Beta for Linux arrived earlier this month with new GPU support for the other Rx 200 series graphics cards. This driver also supports the Linux 3.12 kernels.
Released just days after the AMD Radeon R9 290X ultra high-end graphics card launch this week is Catalyst 13.11 "Beta 6" for Linux. This driver supports the R9 290/290X, but we don't know how well the support is, if there's OpenGL issues, performance bugs, or other issues commonly plaguing the Catalyst driver. Sadly due to AMD's lack of cooperation there's no Linux coverage of this beautiful GPU. Though this week I did publish a Radeon R9 270X Linux review thanks to Phoronix Premium subscriptions and PayPal tips. Thanks to those who helped out!
The latest AMD Catalyst Linux beta can be downloaded via this forum thread.