After viewing these pictures, I have a whole clutch of new obsessions. Stock Tank Pools, retro reused fireplaces outside, rock pile gardens, bigBANG blog, and vintage dune buggies are a few of things I am desperately seeking. Help me! Joshua tree and the desert couldn't be more different than where I cultivate, making my lust all the greater.
Using a large stock tank for a pool is a novel idea that is certainly cheaper and far more hip than a generally less attractive above ground pool or a wildly expensive in-ground pool. Large stock tanks can be had for a few thousand when new (or less when found used and cleaned up). Island Hot Tub has a great write up on where to find new stock tanks, as well as what to look for (all tanks are not created equal) when purchasing a tank to be made into a hot tub or pool.
Alternatively, if you dont' care to swim in the pool yourself, and would rather plant it with aquatics or make a fish home, check out Pam Penick's how to on stock tank pond gardening.