I'm no expert on propagation of Waratahs (genus Telopea) but I do know that the best method of propagation is seed for naturally occuring species and then by cutting for hybrid species. You could certainly try propagation of your cuttings but make sure you remove the flower head and leaves so as to direct as much energy as possible to the generation of roots. Good luck!

More information of Telopea propagation can be found here:
http://www.anbg.gov.au/telopea/index.html
http://www.rbgsyd.nsw.gov.au/plant_info/Plants_for_gardens/Growing_waratahs

And just as a passing observation related to the beauty of the Waratah flower; it's a crying shame to visit our national parks and see that the rangers have to spray the flowers with blue paint to stop visitors from stealing the flowers and deny the plant the opportunity to develop seed and naturaly propagate. The poor old Waratah is too beautiful for its own good against the personal greed of human nature.

Gotta agree wholehartedly with you there Tony. You know I'm onto my 4th white one; all previous attempts have failed, but this one shot up a bit last season after planting and then stopped. Looks healthy enough but won't proceed further! I've a red mongaensis x speciosissima (corroboree) growing and flowering and has done so for the past 5 years but the whites, this one specio. x oreades 'bridal gown', well, seems they're another story.