This salvia is very similar to Salvia greggii, being compact in form (ht 80cm - 1m) and having many cultivars of various colours from which to choose, including pinks, red, cerise, white, apricot and lemon. However, it is more humidity tolerant than Salvia greggii, so I think it is overall is a better plant for Sydney suburbs that have muggy summers. It mixes effortlessly with almost any other style of plant. It flowers over a long period in summer and autumn in a sunny, well-drained spot, and is drought and frost tolerant. A particularly good cultivar is 'San Carlos Festival', which has rich cerise-pink flowers and attractive, dense foliage.
Other good cultivars include 'Hot Lips' with red and white flowers, 'Musk Pink' (baby pink) and 'Pink Blush' (bright pink). It should be pruned in the same manner as Salvia greggii is tackled: pruning the sides of the shrub first and then the centre once regrowth has occurred on the sides. It can also be trimmed lightly to shape periodically through the growing season. Sometimes heavy pruning will kill a plant, especially if it is done in winter. This sort of salvia can be grown in pots and is suited to cottage garden styles with roses and perennials, though it also fits into basically any type of garden. Cuttings of these plants can be tricky: try taking cuttings of fresh growth in spring.
Note that there are now some hybrids between Salvia microphylla and Salvia greggii, called Salvia x jamensis; some examples include the 'Mesa' range, such as 'Mesa Azure' and 'Mesa Purple', which are good plants for Sydney.