The average contract interest rate for 30-year fixed-rate mortgages decreased to 5.73 percent from 6.05 percent, with points increasing to 1.10 from 1.05 (including the origination fee) for 80 percent loan-to-value (LTV) ratio loans.

The average contract interest rate for 15-year fixed-rate mortgages decreased to 5.21 percent from 5.61 percent, with points increasing to 1.18 from 1.02 (including the origination fee) for 80 percent LTV loans.

Bankrate.com is also finding a drop in rates, though not so low:

Mortgage rates declined sharply this week, the first drop in a month. The average 30-year fixed rate declined 17 basis points from the previous week, to 6.14 percent. A basis point is one-hundredth of a percentage point.

Meanwhile, the average 15-year fixed -- a popular option for refinancing -- declined 21 basis points, to 5.76 percent.

Next time I talk to Bankrate.com, I'll ask about the difference. Perhaps its survey doesn't assume a 20 percent down payment, as the mortgage bankers' survey does. Bankrate.com's survey was conducted last Wednesday, while the mortgage bankers' poll concluded Friday.

EDIT at 6 p.m.: Bankrate.com just released its newest survey. Here's what it says:

According to Bankrate.com’s weekly national survey of large lenders, the average 30-year fixed mortgage has an average of 0.35 discount and origination points.

The average 15-year fixed rate mortgage popular for refinancing plummeted to 5.45 percent.

Bankrate.com says it's the biggest two-week drop in rates since May 1995 and attributes it to concerns about the economy.