Designers everywhere are setting text into the screen by giving it a tiny highlight at the bottom edge and an inner shadow along the top to create a digital analog for the “letterpress effect” or de-bossed text. Drop shadows have long been de rigueur on the web, but the letterpress effect is quickly becoming the new go to treatment for the uninspired.
I don’t mind this me-too-ism, it’s how trends catch on. If the letterpress effect is applied with restraint, it serves as a subtle marker of website quality, and by extension the quality of the product or business behind the site. I think that’s why it’s use is quite widespread in the websites of Mac, iPhone & iPad developers. On a subconscious level your eye is picking up those tiny little highlights and mixing it in with other elements of the site to form a gestalt that is both pleasing and razor-sharp.
Like many design trends it had a tipping point. I believe it really kicked in when Adobe transitioned from CS3 to CS4 and all their product logos in the splash screens went from being outies to innies.