Kalanchoe tubiflora (aka Bryophyllum tubiflorum), Mother of Millions, is the noxious weed one. http://www.weeds.org.au/cgi-bin/weedident.cgi?tpl=plant.tpl&ibra=all&card=H14
K pinnata seems to be considered a weed in some places.
http://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Bryophyllum~pinnatum
http://www.townsville.qld.gov.au/resources/3067.pdf