Last night we watched Children of Men (2006,R) (ScreenIt! Review).  From the Wikipedia:

Set in the United Kingdom of 2027, the film explores a grim world in which two decades of global human infertility have left humanity with less than a century to survive. Societal collapse, terrorism, and environmental destruction accompany the impending extinction, with the United Kingdom, perhaps the last functioning government, persecuting a seemingly endless wave of illegal immigrant refugees seeking sanctuary.

I'm surprised I hadn't heard of this one before.  It was fantastic.  I never would have guessed it was a "companion piece to Cuarón's Y tu mamá también."  You couldn't help but think of The Road and also 28 Days Later, and it was interesting for many of the same reasons...but also because so much of it felt so familiar...pervasive anti-immigrant sentiment, soldiers with German shepherds, hooded prisoners, etc.

I give it 5 out of 5.