This is known as indirect object syntax. Camel bible^H^H^H^Hook, pages 295 and 316 :-)

I should also add that this syntax is somewhat frowned upon, due to the potential ambiguities discussed in the "WARNING" section of perlobj. You only stand to gain by choosing to use the '->' syntax instead. As it states:

The infix arrow notation using ``->'' doesn't suffer from either of these disturbing ambiguities, so we recommend you use it exclusively.

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