Size creep, as it has come to be known, is keeping a clothing size's physical measurements the same, but labeling it as a smaller size than it was previously known. It's aimed primarily at women, supposedly to flatter them into thinking they are thinner than they really are, or some marketing BS like that.
J. Crew is practicing reverse size creep; that is, I've had to start buying their clothing in bigger sizes. Their men's size large shirts, and at least one style of sweater, no longer fit me comfortably. They have trimmed the patterns by at least a couple of inches, so while I can button the shirts, there's enough pulling between the buttons to look unattractive. I noticed that the armholes and upper arms are cut more snugly as well. Extra large fits comfortably enough, but the sleeves are a little too long. If anything, they should be going in the opposite direction, given our country's obesity epidemic, or at least consider offering the shirts in more than one fit/cut.