Apple just announced iOS 5.1 at its iPad event today, and among the most significant upgrades are Japanese language support for Siri, and the ability to delete photos from Photo Stream (as we spotted in the 5.1 beta). The 5.1 update also includes an always-visible camera shortcut for the lock screen, improved camera face detection and a redesigned camera app for the iPad, Genius Mixes and Genius playlists for iTunes Match subscribers, support for dictation in English, French, German, and Japanese, hotspot functionality for the iPad, and other minor bug fixes and improvements.

The 5.1 update is available now, with Japanese language support for Siri rolling out in the coming weeks.