Cameras and lenses may have built-in image stabilization. Originally they only indicated the inclusion of such a system. As newer generations of image-stabilization systems came to be, manufacturers started making performance claims but these were best-case-scenarios under unknown conditions and so were not comparable. For this reason, CIPA created a standard testing methodology for image stabilization systems. The result of such testing is a standardized and comparable number of stops of stabilization efficiency.
While most cameras and lenses were not measured according to this standard, already dozens are. The Neocamera Camera and Lens databases have been updated to store that information, when available. The specification pages for Lenses will now include the efficiency computed according to the CIPA standard next to the Stabilization label. It will say, for example, 3.5-Stops, instead of only Built-In. These numbers get compared and highlighted in the Lens Compare Tool and Lens Search Engine.
For cameras with built-in image-stabilization, we have the CIPA stabilization efficiency and the number of correction axes included in specifications. Those models for which the data is not available will still say Built-In. Others will indicated the number of axis and efficiency, for example: 5-Axis, 5-Stops. These numbers get compared and highlighted in the Camera Compare Tool and Camera Search Engine.
This should give a good indicated as to the relative performance of image-stabilization systems. There are additional complexities which are difficult to model such as new Dual IS or Sync IS systems which allow a camera and lens to cooperatively perform image stabilization. For example, the new Panasonic Lumix DMC-G85 features a 5-axis image stabilization system effective to 4 stops yet can reach up to 6 when combined with select stabilized lenses. Also, CIPA numbers are computed with a given methodology and may not represent real-world performance in many cases.