Patch 2.1.3 has gone up on the PTRs, revealing that the next patch seems to be a small bug fix.

World of Warcraft Client Patch 2.1.3

The latest patch notes can always be found at http://www.worldofwarcraft.com/patchnotes/

General

" The Warlock spell Incinerate has had the performance of its graphical spell effect improved.
" The "show launcher" option has changed so that it now defaults to "on". Players will now see the launcher when running WOW by default.

User Interface

" Improved the performance of conditional macros, slightly increasing the framerate.
" Fixed a crash triggered by many unit frame AddOns.

Bug Fixes

" Fixed an issue with the movement of Archimonde's Doomfire.
" Fixed the wand missile art on most Shadow based wands to show the correct graphical effect.
" Infinity Blades will now despawn properly when the encounter with Kael'thas resets after a wipe.
" Gan'arg Underlings and Felhound Defenders are now properly classified as demons.

Most notably, the fix to the unit frames crashes may fix the recent lockups experienced while reconnecting inside a raid instance.

Along with the new patch, Hortus has posted a much needed FAQ for the test realm, which will hopefully quell the cries of "OMG RELAMZ R DOWN PLS FIX BLUE" that accompanies every bout of PTR activity.