The ros_rt_wmp is a ROS node capable of replicating whatever ROS topic or service in another computer wirelessly connected with the source without the need of sharing the same roscore.
As an example consider a team of robots building cooperatively a map. The robots have to exchange their laser and pose information. However if the network that connect the robots is not completely connected and they can't use an infrastructure network (an outdoor chain network for example) there is no way to share data among robots using the ROS.
The ros_rt_wmp allows to distribute/decentralize a complex robotics system in multiple computation units in a transparent form: the only requisite is to know which data from other robots we need in each one of them.