WWDC

Short for Worldwide Developers Conference, WWDC is an expensive ($1000+) gathering for Mac and iPhone developers. It includes various sessions for developers as well, as a keynote to kick it all off. The keynote is public and available for download through the podcast "Apple Keynotes" (SD/HD) on iTunes. The developer sessions are semi-private and available with a free or paid Apple Developer account.

2008 Keynote

 * MobileMe announced and demonstrated
 * iPhone 3G announced and demonstrated
 * Push Notification Service for developers announced
 * Countries that the iPhone 3G was and still is planned to be released in announced

2009 Keynote

 * iPhone 3GS announced. A working model was not shown.
 * Push Notification Service announced for iOS 3.0

2010 Keynote

 * iPhone 4 announced and demonstrated.

2011 Keynote

 * iOS 5, iCloud, and Mac OS X Lion announced.

2012 Keynote

 * iOS 6