Coming in First/Last

What does it mean for Jesus to say "the last will be first and the first will be last"?  No, really, what does that mean?  In Matthew 20 He tells the story of the guy who hires people to work for him, and pays them all the same, even though they all worked different lengths of time.  When people complain, the landowner says "don't complain because I'm generous".  What does this all mean?

How do I complain to God about His fairness and grace?  I think personally when other people who don't love Jesus get away with stuff, I get upset.  When people around me whine, or lie, and I am expected to work harder to cover for them, I get mad.  When I have to do jobs I don't like, and other people don't, I get indignant.  It's because I forget maybe the key part to the story.  God is the landowner.  No one else is.  I work for Him, no matter what "field" I'm in at the time.  I mean, I serve as a dad, husband, son, friend, co-worker, pastor, mentor, professor, etc.  Each of those is a different "field".  But it's all for my Boss, who owns it all. 

When I remember that He is the One in charge of every facet of my life, that He is the One who has put me there, I calm my little self down a bit.  It's all fair in the grand scheme of things, because the Landowner who oversees it all is full of grace.  Don't worry about it.  Keep moving forward.  It will all work out in the end.