What is the best way to transform the following:
Item Due Date
001015 11/5/2012
001016 10/22/2012
001016 11/5/2012
001016 11/19/2012
001016 12/3/2012
001020 10/29/2012
001020 11/19/2012
001020 12/10/2012

Into:

Item Date1 Date2 Date3 Date4
001015 11/5/2012
001016 10/22/2012 11/5/2012 11/19/2012 12/3/2012
001020 10/29/2012 11/19/2012 12/10/2012