I read a great article the other day, Free-Range Landscaping , in the Wall Street Journal. Eco-entrepreneurs are using goat herds to maintain lawns without chemical weed killers or noisy, air-polluting mowers. The friendly critters really take to the job, devouring all manner of grass, weeds and even thorny brush. They love steep slopes and happily "work" all day long munching away. The even will fertilize for free!
Perfect for brush, I think the goats might get a little carried away on your lawn, trimming it a little too tight for a healthy, drought tolerant lawn. Remember: keep your lawn at least 3" high to promote deep roots, shade out weeds and withstand the heat.
The best solution? Plant a Pearl's Premium lawn, which grows at 1/4 the rate of a traditional blue grass lawn, and leave the goats for the brush.