In commercial printing, process by which many copies of an image are produced by repeated direct impression of an inked, raised surface against sheets or a continuous roll of paper.
Letterpress is the oldest of the traditional printing techniques and remained the only important one from the time of Gutenberg, about 1450, until the development of lithography late in the 18th century and, especially, offset lithography early in the 20th.

One of the most unexpected trends was the emergence of letterpress (actually pressed letters) in Web design. Probably the most important reason for this trend is the simple fact that this technique has been rarely used in web but it was proven effective and very eye cathcing
Online Services, NGO’s, Service Oriented companies used this commercial printing techniques in web.
Smashing magazine featured Letterpress as Web Design Trends For 2009, which I really foreseen long time before.
I incorporate the letterpress in some of my design such as Basic Golden Frame, Free Church Website and Hills Ville which you can download as WordPress Theme and CSS Layout including the original psd.