I couldn't quite make out the tiny yellow markings on the side of the eyes, but Amphylaeus nubilosellus was the closest match I could find/think of. It is just an educated guess though! Seen on a garden callistemon in the lower Blue Mountains, NSW.
Thank you for letting me know, Michael! I appreciate that and will record its I.D. when I get around to uploading the photos to Flickr. Hopefully the name will start to show on the species list here! I am currently holding out for an I.D. of another bee I saw at Winburndale Nature Reserve in the Bathurst district. If you have the time, I'd love it if you could take a peek: Apiformes (informal group) (Unidentified bee) Thank you. :) - Tessa