How soon they forget! It wasn't an Apple 'special event', it was the perennial San Francisco MacWorld Expo, once the go-to event for Apple announcements.
Apple's moved on from MacWorld as a launch platform, and I wouldn't be completely surprised if Apple someday owned their own general-audience conferences – believing, as with retail stores, they should control the whole experience.
But MacWorld Expo shouldn't be written out of Apple history.
The original iPhone was announced at a special event on January 9, 2007.
iPhone 3G was announced at WWDC 2008.
iPhone 3GS was announced at WWDC 2009.
iPhone 4 was annouced at WWDC 2010.
iPhone 4S was announced at a special event on October 4, 2011.