The new Blogger interface makes me feel uneasy about writing a short post. But I’m writing one anyway. From The Elements of Typographic Style Applied to the Web:
Anything from 45 to 75 characters is widely regarded as a satisfactory length of line for a single-column page set in a serifed text face in a text size. The 66-character line (counting both letters and spaces) is widely regarded as ideal. For multiple column work, a better average is 40 to 50 characters.The line in Blogger’s new text-box is much too long for comfortable composing and editing. I do like the orange though.
Blogger’s fresh new look (The Official Google Blog)