Announcement from simulator_gazebo maintainer John Hsu to ros-users
On the Gazebo side, major changes from Electric simulator_gazebo (pre gazebo-1.0.0-RC) to the Fuerte version (gazebo-1.0.0-RCX) can be found on the Gazebo change list wiki page. Notably, the new Gazebo plugins have been redesigned to be more flexible to the end-users, but unfortunately, this means the new plugin API is not backwards compatible with the old version. To convert old style plugins to the 1.0.0-RC plugin, please take a quick look at the plugin tutorials, in particular, this tutorial tries to provide an overview on the conversion process. For additional reference, you can also take a look at the updates in gazebo_plugins and pr2_gazebo_plugins packages. For questions or troubleshooting the conversion process, please make use of ROS Answers or the gazebo mailing list.
Lastly, you might have noticed that the gazebo project has been migrated from sourceforge to kforge (see the gazebo project page on kforge), please submit gazebo-specific tickets to the new trac and feel free to checkout the mercurial repository.