"Hey Siri" support and possibly wireless charging case alongside AirPower charging mat.
iMac Pro Appears to Include A10 Fusion Chip for Always-On 'Hey Siri'
As noted by Troughton-Smith, the A10 will manage the booting process and security for the iMac Pro, and with hooks into system audio, he theorized that the chip might support always-on "Hey Siri."
Confirmed: "Hey, Siri" is coming to the Mac pic.twitter.com/Dw9bRAzbxD— Guilherme Rambo (@_inside) November 18, 2017
BridgeOS has a boot chime sound pic.twitter.com/ofupY9RZt8— Guilherme Rambo (@_inside) November 18, 2017
In June, Pike's Universum reported that the upcoming iMac Pro will include a Secure Enclave, suggesting the machine would indeed include an ARM-based coprocessor as on the MacBook Pro.
Unveiled at WWDC in June, the iMac Pro is scheduled to launch next month, but Apple has yet to give a specific launch date for the high-end desktop that will start at $4999.