Google redesigned following AdSense for content ad units! to make formats more space-efficient and visually pleasing by changing the layout of the text. "In addition to under metioned changes; In certain cases, you'll also see a few minor adjustments to font size. During testing, new ads performed extremely well," informs Google.
The ad units: » Leaderboard (728x90): the title, description, and URL are now arranged in rows instead of columns (except in when only one ad is showing) and » Medium and large rectangles (300x250, 336x280): URL is now in same line as the title.