At 00:57 GMT space shuttle Endeavour launched successful. The space shuttles payload contains special equipment and modules to upgrade the ISS for a bigger crew. The shuttle has been launch right on schedule with only several small errors, like a door inside the shuttle which wasn't secured for 100%.
This mission will change the ISS for more than a small bit. A bigger crew means the ISS is getting more important. It also means that there will be made more flights to change the crew and bring new food. This will result in spacecrafts which will be cheaper and better to use. The upcoming rocket to blow the space shuttle aside will be the Ares rocket.
No other blog is better to read than the Nasa STS-126 blog itself: