I was trying to round up the release dates for Macromedia Flash and the Flash Player (plug-in). I scoured the web and here's what I found.. if you have a more specific date for any of these please contact me.

Flash 9 (CS3) released late March 2007
Flash Player 9 (originally named 8.5) Beta available to developers March 2006, released to public June 2006

Flash 8 released mid September 2005
Flash Player 8 Beta available to developers July 2005

Flash MX2004 released September 2003
Flash 7 player Beta available to developers Aug 2003

Flash mx released - march 2002
Flash 6 player Beta available to developers Feb 1, 2002

Flash 5 released - Fall 2000
Flash 5 Player released - July 2000

Flash 4 released - July 1999
Flash 4 player released - May 1999

Flash Player 3 released Spring 1998