Vivian Toy in a 2007 New York Times article describes the value of hiring a pro to photograph real estate listings.
(Added 22 October, 2009)

How many photos should a listing display? A recent study (2008) concluded Real estate listings with 21 or more photos generated more than triple the number of detailed views, more than double the amount of interest, and double the number of leads.

In real estate, where 80% of buyers browse the Internet, buyers show more interest in listings on pages with a quantity of photos necessary to provided full coverage of the property. Furthermore, high quality images contribute to the buyers' decision to investigate listings further, through actual site visits. (Added 22 October, 2009)

In January 2011, American analyst Barbara Corcoran appeared on the Today Show and offered these 5 tips on marketing a home. Prominent among Barbara's recommendations is tip #5: "Wage war online. Everyone goes online to find the home. If your home doesn't look good online they are not going to bother coming to see it." Barbara recommends photos taken by professional photographers to attract buyers on web listings. Images that help a home shine online is perhaps more important when there is a lot of inventory available and when markets are tight. It appears that the local market is following the trends set by the American markets to the south.