Back in October, Wryxian announced on the official European forums that Blizzard was working on combining battlegroups of different languages to create higher populations for both battlegrounds and arenas. Well, the Cross-Language Battlegroups are now available for testing on the PTR, and this weekend's testing will be focused on battlegrounds. Here's when you can participate:

"On Saturday 28th of March, focused Battleground testing will take place between 18:00 and 20:00 CET. On Sunday 29th of March, focused Battleground testing will take place between 16:00 and 20:00 CEST (remember to adjust the clock!)"

You can read Wryxian's full announcement here. Not all battlegroups will be merged, and the Russian-language one will not be affected.