ISD team build
The first team build of the ISD occurred at BricksWest 2003 in Carlsbad, California. The time for the build was 1 hour, 48 minutes. The rules were very loose, as this was merely a "let's see if we can do it" event. Through the help of Jake McKee and Kate Sutch at LEGO Community Development, an ISD was provided by The LEGO Group for each event.
Following that event, another team in Europe decided to do the same (event-1000Steine?), but beat the time. The time there was (needs update). From that point, the race was on to continually beat each other's time.
Various times, notably during cooresponding BrickFest and 1000Steine conventions, the time kept being whittled down by 1-5 minutes per event. The final recorded event was a timed build not at a convention, but at the LEGO store located at the Solomon Pond Mall in Marlborough, Massachusetts, by LEGO fan group NELUG (New England LEGO Users Group). The final time of that build was approximately 59 minutes. Over the course of roughly 3 years, the 1 hour mark had been broken. With the gray color change, and the advent of a larger set (Death Star II), the interest in this building event started to wane.
8421 crane speed build
Death Star speed build
A list of speed building records can be found at http://www.recordholders.org/en/list/lego.html (a web site dedicated to LEGO world records).