As of January 2014, Imageshack moved from imageshack.us to imageshack.com, redesigned the site, and eliminated free hosting. They now only offer a paid subscription model and free 30-day trial. After 30 days, if you don't pay up your pictures stay but you can't upload. The same applies to anything you had on the old imageshack.us - pay up or no more uploads.
Reference: http://imageshack.com/promo (scroll down to read the Q&A)