Blizzard have now posted a list of the EU realms which will have voice chat enabled as soon as patch 2.2 goes live. They are:

* English
Earthen Ring, Ravencrest, Runetotem, Shadowmoon, Shadowsong, Shattered Hand, Silvermoon, Skullcrusher, Spinebreaker, Stormrage, Stormreaver, Stormscale, Terenas, Thunderhorn, Turalyon

* German
Aegwynn, Alexstrasza, Alleria, Antonidas, Baelgun, Blackhand, Destromath, Die Silberne Hand, Eredar, Frostmourne, Frostwolf, Gorgonnash, Gul'dan, Kel'Thuzad, Kil'Jaeden, Madmortem, Malfurion, Mal'Ganis, Mannoroth, Nathrezim, Nozdormu, Perenolde, Proudmoore, Zirkel des Cenarius, Zuluhed.