On 2008-01-28, Wayne Whitney wrote:

While there is a change in the 2008 NEC regarding multi-wire branch
circuits (MWBCs), it does not make them illegal. In the 2005 NEC,
if the MWBC served a single yoke with multiple devices, then a means
of disconnecting both legs simultaneously is required. In the 2008
NEC, this is always required. The practical implication for
residential work is that you have use a double pole breaker.

That should say that you have to use a double pole breaker with handle
tie.

Cheers, Wayne