SIOCADDMULTI for unicast broken

Some programs require ability to accept packets destined to certain
MAC addresses (in addition to their own).
Example Jerome Ettienes vrrpd (http://w3.arobas.net/~jetienne/vrrpd/)

The trick is to add unicast addresses via SIOCADDMULTI and accept those
packets when they make their way up the stack.
I think this used to work, no? Donald, any history/comments behind
this?
Patch attahced, not very well tested but looks safe.

cheers,
jamal