The feature will be used extensively by Ghost Recon Online.
During Nintendo's second press conference, Ubisoft was in attendance and they confirmed some new details regarding their coming Wii U game, Ghost Recon Online. According to Yves Guillemot, Ghost Recon Online will feature extensive voice chat, meaning Wii U itself will support the feature. Seemingly the microphone on the Wii U controller will be used for this feature, but because all Wii accessories will work with Wii U, Wii Speak may also be compatible.