ROS 1.3.1 has been released, including the ros_comm 1.3.1 stack. We
expect that this release will break a small number of packages, though
there are instructions below on how to deal with this.

This release contains major changes to ROS, which are described in REP
100 [1]. The ROS stack has been separated into several stacks: ros,
ros_comm, rx, and documentation.  This move required many significant
changes, including:

 1) Moving roslib/Header into std_msgs
 2) Moving roslib/Clock and Log into rosgraph_msgs
 3) New rosunit testing library to complement rostest
 4) New packages to support roscpp

There are many more changes described at:
http://www.ros.org/wiki/ROS/ChangeList/1.3#A1.3.1_.282010-11-19.29

We expect this update to cause instability in "unstable", so we do not
recommend that users update to this release in their main development.
We do recommend that people test against this new release to see if
there are any issues and provide feedback. You will need to install
both ros and ros_comm now to test against.

In our own testing, the moving of roslib/Header has caused some
roscpp-based code to fail. If you're code passes around references to
roslib::Header, it will fail to compile because Header now resolves to
std_msgs::Header. We have been able to resolve this in our code by
either:

 a) Template on the Header type
 b) Re-evaluating the method signature (e.g. const-ness, whether or
not a full Header instance is required)
 c) Use macros to conditionally compile based on ROS version (e.g.
ROS_VERSION_MINIMUM macro).
 d) Changing to std_msgs::Header (not backwards compatible)

 -- your friendly neighborhood REP 100 team

[1]: http://www.ros.org/reps/rep-0100.html