SpaceX Launch Update: This Sunday SpaceX will attempt to launch the first Falcon 9 v1.1. While similar to the original Falcon 9, the upgraded version sports the more powerful Merlin 1D engines which have yet to fly, a much longer fuselage, a new larger fairing and a number of other upgrades to the rocket including its software. The launch will be webcast.
The primary payload is the Canadian Space Agency CASSIOPE satellite. Several secondary nanosats will also be launched.
SpaceX is categorizing this launch as a "demonstration flight" with the risk higher than usual for a Falcon 9 launch. However I don't expect them to launch unless they are as certain as they can be of mission success.
UPDATE: SpaceX has successfully launched the Falcon 9 v1.1 on its maiden flight.