Mortgage rates have been improving lately due to pessimism about the US economy. Those considering a refinance or a home purchase should take advantage of these low rates. Mortgage rates will rise in the near future when our economy continues to shoe signs of improvement.
Mortgage loans are sold as bonds. When people feel pessimistic about the economy they buy "safer" investments, re: bonds.
Buying bonds causes mortgage rates to drop. Selling bonds causes mortgage rates to rise. The Fed has nothing to do with mortgage rates so when you see ads that say the Fed lowered interest rates they are not talking about mortgage rates. They are talking about the rates banks charge each other. Don't be fooled.