From the NASA site, where you can watch the liftoff.

The Closeout crew is continuing to prepare Endeavour’s crew module for closeout for flight. The hatch is closed and cabin leak checks will be conducted. The astronauts continue to go through final checks inside the orbiter to prepare for their journey to the International Space Station.

There is only a 10 percent chance of weather prohibiting a liftoff at 6:36 p.m. EDT.

Mission STS-118 will be the first for Mission Specialist Barbara Morgan, the teacher-turned-astronaut whose association with NASA began more than 20 years ago. First Lady Laura Bush called Morgan Tuesday morning to offer congratulations “one schoolteacher to another,” and to thank her for her commitment to the space program and to education.