Processing of the space shuttle Atlantis continues today, July 4th, in preparation for the July 8 launch.
Here are the launch windows for Atlantis (times are UTC):
After that is a five day period reserved for a Delta IV launch. The next launch window is 16 July beginning at 1211 UTC.
The primary objective of STS-135 is to deliver a Multi-Purpose Logistics Module (MPLM) carrying 9,500 lbs of cargo, a Lightweight Multi-Purpose Equipment Support Structure Carrier (LMC), and a Station Power Distribution Unit (SPDU). The LMC will carry the Robotics Refueling Payload to the ISS and return the failed Pump Module (PM) from the ammonia cooling system. Additional ISS equipment and supplies will be carried up.
The current mission for Atlantis is to deliver as much stuff as possible to the Space Station before we come to rely on the Russian Soyuz M, European ATV, Japanese HTV, SpaceX Dragon and Orbital Sciences Cygnus resupply missions.
A long history of the Atlantis missions can be found at NASASpaceFlight:
A complete guide to NASA TV coverage can be found here.