I just spent a few minutes on WDWMAGIC.COM glancing through the history of this attraction. Wow, it's been 3 full years since the demolition of the Horizons building. Construction on M:S started shortly thereafter. Seems like AK was completed in less time than that.
For us nerds, we track this stuff all the time. But, I'm wondering what the not-so-engaged annual visitor thinks.
April 2000 trip to Epcot - they see the Horizons building being demolished.
April 2001 trip to Epcot - they see the shell of the Mission:Space building.
April 2002 trip to Epcot - the building looks basically complete, wow this is taking a while, but it must be opening soon.
April 2003 trip to Epcot - looks virtually the same as a year ago. What are they doing in there? Is this thing ever going to open?
Come to think of it, they were probably conditioned to the timing by Test Track, eh?