Learn a bit about their business domain / tech domain, such as "consumer facing web apps", spend some time going over your skill-set and experience and determine how you can map your current experience to the skill-set they would be looking for. Already being a programmer, you are bound to be more adaptable than someone who is just starting out, its just a matter of having the right perspective to adapt your skills and selling your prospective employer on the fact that you area able to do this.
Somewhat related, at my current job, they hire senior dev's to work on an existing web application that uses JSP's, AJAX, JavaScript, etc who have little to know experience with web development (but know the server-side language well) because they are confident in their overall dev skills and adaptability, I think the same logic would apply to your situation.