The old saying "what is old is new again" seems to be the rule for current window treatment trends. I had not seen cafe' curtains in years but now they are back and popping up everywhere. This is a very versatile style that can be used alone, with top treatments and as an additional layer with panels. The appeal of this little half curtain is that it allows light and privacy all at the same time.
The length of the cafe' curtain is traditionally from the mid-point of the window and will line up with the center sash. Not as commonly used but still attractive is to raise the rod up higher on the window to the next mullion for example. This gives a generous curtain that allows even more privacy. The grommet curtains below only cover the bottom third of the window which is just enough to provide privacy while sitting at the desk. It seems the new version of the cafe' curtain is not following any rules.
Source: Southern Accents Magazine
Cafe' curtains can be found in sheer or lined materials. Blackout isn't usually used because the purpose is just privacy and not light blocking. The heading style can be as simple as flat panels with minimum fullness and clipped-on rings or another flat panel style is grommet panels as seen in the photo. For more fullness gather by shirring on a rod or use a pleated heading. In the photo below the spaces between the pleats have been cut at a soft curve, giving a custom touch to the finished curtain.
Barbara Duncan Interiors, Richmond, VA