The Wire library has while loops that could go on forever. Although this will not happen in a normal situation, if it happens, the blocking stops the Arduino from working and that could be a safety issue.

Arduino version 1.0.5

A simple loop as timeout could solve this, as suggested here, http://diydrones.com/forum/topics/i2c-wiring-library-lockup
A non-blocking version was also made in 2011 by gknight4, http://forum.arduino.cc/index.php/topic,70705.0.html