Before getting into the article, a quick introduction to vignettes:
Vignetting refers to in its most general sense any technique that is used to frame the subject. In its original usage, it referred to the decorative practice of putting a vine motif around the edge of a book, hence vigne or vignette. In photography, it generally refers to adding in a gradient of color (de)saturation, light or dark around the edges of a photograph to varying degrees in order to better highlight the center of the photograph—or if you're feeling adventurous, off-center.
Vignetting may be accomplished through a variety of means. Vignetting occurs naturally with many digital imaging sensors, which may or may not be desirable. It may also be created in virtually all image editing software, or with specialized lenses and filters.
This may achieve a variety of effects in the photograph, depending on the context—and the type of vignette. As with all photography, use of vignettes is quite subjective, so feel free to experiment.