Don’t buy right now, you’d obviously be catching a falling knife.
Lots of things could happen. On a positive side, gas prices could stabilize at $4/gallon or lower, people could start carpooling more and it would reduce the congestion on I-15 south. A number of next-generation hybrids are coming on the market around 2010 (VentureOne, Aptera, new Prius PHEV, Volt, …) so we can learn to live with high gas prices. Affordable housing can draw more employers into the area.
On the other hand, gangs, squatters, and desert could move in, and soon you’d find yourself in a ghost town.
It’s up to the municipal government whether Temecula will find its bottom in an orderly fashion (for a pretty city filled with 3000 sf new McMansions, there’s got to be a bottom somewhere ), or run into the ground.