Grevillia

There are hundreds of Grevillia species that are endemic to Australia. They cover a wide range of sizes - from compact ground covers right up to 35-40 metre high trees - and colours - from creams, yellows, oranges and pinks through to reds - even deep reds verging on crimson - through to pale lavenders.
After a quick whip around some Google results, my official hunch is that this is a Grevillia rosemarinifolia, because 1.) they sorta look like the photos of that species that I've found online; and 2.) their foliage looks a little rosemary-ish to me. Happy to be advised otherwise.
Think the girls in the Flow hive have been eagerly awaiting these flowers, because as soon as there was the slightest flush of pink on the tree, they became very busy sniffing around for some nectar. 
Some of the native birds have been very keen, too - especially the honeyeaters and the rainbow lorikeets, and the nemesis of both, the noisy miners.
While many of the flowers appear delicate, lush and spindly, the plants themselves are as tough as old boots, and need very little TLC to maintain. A splash of water every now and then (but don't overdo it), and a light prune when flowering is complete, and chances are, the plant will thrive. 
The flowers of many species are sought after by traditional, on-country Aboriginals across Australia for their sweet nectar. However the flowers of some of the cultivars used in suburban gardens produce a cyanide-like substance along with the nectar - which is never a good way to get a sugar hit.