According to a TIL article, there will be an update to PlainTalk 1.5 which will make it iMac-compatible. PlainTalk Speech Recognition 1.5 requires a PowerPC-based computer with sound input at 22.050 kHz, which the iMac doesn’t have. The iMac only has sound input at 44.100 kHz.

Apple’s speech technologists are currently working on a version of speech recognition for the iMac and DVD cards, and when ready it will be downloadable for free from www.apple.com/speech.

Apple remains committed to further development of its advanced speech technologies and their integration into the User Interface.