Yesterday, NASA was supposed to launch their $445 million rocket prototype, Ares I-X, but the launch was delayed due to bad weather conditions.
Today, NASA is poised for a second attempt, with the launch window being 8 a.m. to noon EDT. Just like yesterday, the weather isn't cooperating, but the launch might still happen if NASA's experts conclude that the conditions are safe enough.
You can watch the launch attempt over at NASA TV (or below) and follow the latest developments regarding the mission on the official NASA page.