Perhaps to coast on the familiarity of the Facebook layout, or maybe just because, Twitter has made a change. The “what’s happening” box where you enter your 140 character words of wisdom, jokes, outrage or white sales announcements has moved.
Located at the top center of your timeline (formerly located at the top upper left of the page) it looks just like Facebook. Will this make it easier or encourage more people to tweet? Who knows. Apparently 50% of the folks out there are just lurkers and not participants. Twitter thinks it will make things easier for you. Time will tell.