I was previously mistaken. The binding you're probably wanting is CurrentDateTime. CurrentTime is a short time string.
Both however are a part of the View (which is passed as the DataContext to your controls) and NOT a static variable so you wouldn't be able to look it up on MSDN. The binding would look like:
{Binding CurrentDateTime, StringFormat='{}{0:MMMM dd, yyyy}'}
Again though this string format is saying you only want the Month Day, Year so no time would be displayed.