"Hey Siri" support and possibly wireless charging case alongside AirPower charging mat.
AirPods and AirPower: Everything We Know
Security Update 2006-003 [Updated]
Now in Software update:
Security Update 2006-003 is recommended for all users and improves the security of the following components.
Flash Player Plug-in
Security Update 2006-002 was issued two months ago, in March.
[Update] See these pages for manual downloads:
Mac OS X 10.4 (PPC)
Mac OS X 10.4 (Intel)
Mac OS X 10.3