Preview at WWDC likely in June, followed by September launch.
'iPad Mini' Media Event Also Streaming via Apple's Website
The video stream requires Safari 4 or later on a minimum of Mac OS X Snow Leopard, or iOS 4.2 or later for those accessing the stream from a mobile device. Streaming via Apple TV requires second- or third-generation Apple TV with a minimum of software version 5.0.2.
Apple's event kicks off at 10:00 AM Pacific / 1:00 PM Eastern, and MacRumors will have full coverage of the event's announcements.