I don't think the effect can be explained as easily as "my house was worth X, now it's worth 80% of X", which is typically where your interest lies on the real estate/mortgage thread. I know you're weren't making that claim, but I wanted to clarify in case someone else might benefit from the reassurance their home's value hadn't fallen to that degree. When you have a decline in values that's broadly effecting everyone it'll make lenders risk averse and that hasn't happened in Austin (with the exception of Citibank).
To your point, I'm sure downward price pressure exists, even on the new construction side but it's not being revealed in sales prices (this is an exaggeration, but a builder would rather give you $50K in incentives than reduce the sales price by $10K, that's how hard-wired they are on fighting for sales price). The place to tease that out is on profitability and I haven't seen that data.