Powershell, 78 characters
0..(6*($n=read-host)-1)|%{" "*$_+("*"*(12-($k=1+$_%6*2))+" "*$k)*(.4+$n-$_/6)}
Bonus, 92 characters
$a=0..(6*($n=read-host)-1)|%{" "*$_+("*"*(12-($k=1+$_%6*2))+" "*$k)*(.4+$n-$_/6)}
$a
$a|sort
The output is stored in an array of strings, $a, and the reverse is created by sorting the array. We could, of course, just reverse the array, but it would be more characters to type :)
