Just because someone said it can't be done in one line, I had to try:

use warnings;
use strict;

my %hash = ( 1 => 'one' , 2 => 'two' , 3 => 'three' );

# Here is the one line!
my( @one ) = @hash{ my( @two ) = keys %hash };

# This line is just to demonstrate it worked.
print map { "$two[$_] => $one[$_]\n" } 0 .. $#two;
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Turns out you can do it in one with a slice. Roy_Johnson's approach deserves a ++ though, since it is actually legible. :)