http://puzzles.usatoday.com/sudoku/?POE=SULFLN#/2011/9/16

Fill the 1st Order squares:

Fill the 2nd Order Squares;

Key step to move forward: found only one place for the 5 in row 6 , in (6,9)

Fill the direct consequences of (6,9): (1,7),(5,8),(6,2),(9,1),(5,2)

Fill the rest: (9,3),(1,1),(8,1),(6,6 from 2679 6th col),(4,4),(6,7),(6,3),

(2,8),(1,5),(1,9),(8,6),(9,9),(5,4),(4,1),(4,7),(4,8),(4,3)etc.