SpaceX CRS-2 mission a "go" for this Friday.

NASA has the launch scheduled for 10:10 am EST on March 1st.  The mission will be launched from Cape Canaveral's Space Launch Complex 40 (the site of the previous SpaceX launches).

The mission will deliver around 1,200 pounds of supplies to the ISS and, more importantly (as pointed out in this post), return more than 2,300 pounds of equipment and experiment samples to Earth.

SpaceX Dragon Spacecraft being prepared for launch at Cape Canaveral.

The seemingly small 1,200 pound payload is due to the fact that, like the first resupply mission, the majority of the cargo will be flown in the pressurized capsule section.  However, unlike the first mission, the unpressurized trunk will be used for the first time.  The trunk will be used to send a pair of "heat rejection subsystem grapple fixtures" - presumably too large to fit into the pressurized capsule.  But accessing the trunk requires new procedures - which will be a big objective of this mission - because the trunk is not accessible via Dragon's docking hatch.  Accessing the trunk requires the ISS's robotic arms: the Special Purpose Dexterous Manipulator (SPDM also known as Dextre) and perhaps the the Space Station Remote Manipulator System (SSRMS also known as the Canadarm - and is the same arm that grabs the Dragon to pull it into the ISS dock).
These systems are routinely used for remote manipulation, and accessing the Dragon's trunk should be no problem for these systems, but it is a major milestone and key to unlocking the Dragon's full lift capability.

For further reading, the most comprehensive article I've found on CRS-2 (aka, SpX-2) here at NASASpaceflight.com.