Quote:
Originally Posted by
WalkTheCourse 
They're certainly legal...
They are certainly NOT legal. From the USGA rules:
4. Clubhead
a. Plain in Shape
The clubhead must be generally plain in shape. All parts must be rigid, structural in nature and functional. The clubhead or its parts must not be designed to resemble any other object. It is not practicable to define plain in shape precisely and comprehensively. However, features that are deemed to be in breach of this requirement and are therefore not permitted include, but are not limited to:
(i) All Clubs
- holes through the face;
- holes through the head (some exceptions may be made for putters and cavity back irons);
- facsimiles of golf balls or actual golf balls incorporated into the head;
- features that are for the purpose of meeting dimensional specifications;
- features that extend into or ahead of the face;
- features that extend significantly above the top line of the head;
- furrows in or runners on the head that extend into the face (some exceptions may be made for putters); and
- optical or electronic devices.