If you are shopping for a mortgage in today’s volatile mortgage market, it is a good idea to lock in the interest rate and loan costs.  In the first half of 2008 interest rates ranged from 5.48% in January to 6.45% recently.  The purpose of a rate lock is to protect a home buyer from rising interest rates by guaranteeing the interest rate that your mortgage will have.  Otherwise, by the time your purchase has closed if rates have risen, a buyer could end up with a mortgage payment that they could not afford.  since the lock is for a specific period of time, usually from 15 to 60 days, it is necessary to be sure that your home purchase can close within that time period.
For a more in depth article read Mortgage Rate Locks Become Crucial in Realty Times.

If you would like information on the Central Virginia real estate market, I would be glad to assist you.