I am currently looking at purchasing a new home. I can honestly say that having a REAL professionally-taken photo of the house being represented is a tremendous advantage to the seller and the selling agent. A really good photograph can really accentuate the nice features of a home; and contrarily, a bad photo can make the not-so-nice features of a home REALLY bad. I am less likely to consider the houses that have poor pictorial representation.
I definitely think there is a need for that line of work, but I would walk into a real estate firm with a business portfolio with photo samples to sell your work to the agents.