What year is it?

Python 3, 178 bytes

s=input();i=42157313>>s.index("#")*4&15;print("Your calendar is for %d.\nIt's almost 2015.\n%sGo buy a new calendar!"%(2014-i,(i>0)*("You're %d year%s behind.\n"%(i,"s"*(i>1)))))

A simple lookup table based on the location of the first #.

Expanded:

s=input()
i=42157313>>s.index("#")*4&15
print("Your calendar is for %d.\nIt's almost 2015.\n%sGo buy a new calendar!"\
    %(2014-i,(i>0)*("You're %d year%s behind.\n"%(i,"s"*(i>1)))))

Perl - 187

$ARGV[0]=~/^( *)/;my@a=(7,8,3..5,0,6);my$b=($a[length$1]+2006);print"Your calendar is for $b.\nIt's almost 2015.\n".($b<2014?"You're ".2014-$b." years behind.\nGo buy a new calendar!":"")

CJam, 126 bytes

"Your calendar is for "2e3q'##"DE9AB6C"=~+".
It's almost "2015_(".
You're 5 years behind"9@5$-:TtTg*".
Go buy a new calendar!"