I think no_slogan's will probably be the shortest, but here's some more fun with regexes at 49 chars:

sub reduce { "@{[map 1x$_,@_]}"=~/(1+)\1* \1+$/;map$_/$+[1],@_ } [download]

Update: Here's a 48-char version that uses a relatively fast algorithim for calculating the GCM of the two numbers (I think it's attributed to Euclid?):

sub reduce { ($x,$y)=@_;($x,$y)=($y%$x,$x)while$x;map$_/$y,@_ } [download]

   MeowChow                                   
               s aamecha.s a..a\u$&owag.print