New OS Languages: None
New Keyboards: Hindi, Hawaiian
New Dictionaries: Hindi, Hawaiian, Estonian, Latvian, Cherokee
(Keyboards still without dictionaries: Bulgarian, Icelandic, Macedonian, Serbian, Tibetan)
(Fonts still without keyboards: Gujarati, Gurmukhi, Tamil, Telugu, Sinhala, Oriya, Malayalam, Kannada, Bengali, Armenian, Georgian, Lao, and Yi)
Note that SIRI is only available on the iPhone 4S and is not part of iOS 5 for other devices at this point.