This exact situation was exactly why this rule was enacted. I found the story about it on the net a year or two ago, I'm sure if you google around a bit you can find it too.
5.09
The ball becomes dead and runners advance one base, or return to their bases, without liability to be put out, when --
(a) A pitched ball touches a batter, or his clothing, while in his legal batting position; runners, if forced, advance;
(/cool.gif" style="vertical-align:middle" emoid="B)" border="0" alt="cool.gif" /> The plate umpire interferes with the catcher’s throw; runners may not advance.
NOTE: The interference shall be disregarded if the catcher’s throw retires the runner.
© A balk is committed; runners advance; (See Penalty 8.05).
(d) A ball is illegally batted; runners return;
(e) A foul ball is not caught; runners return. The umpire shall not put the ball in play until all runners have retouched their bases;[/i]