Details
Description
WMS has limits (memory, rendering time, rendering errors)
http://docs.geoserver.org/2.0.x/en/user/services/wms/configuration.html#request-limits
and so does WFS (max features)
http://docs.geoserver.org/2.0.x/en/user/webadmin/services/WFS.html
WCS could use some type of restrictions to prevent overeager users from accidentally or deliberately pulling down overlarge amount of raw raster data.
The limits have been added on both 2.0.x and trunk, along with some overview usage control in the wcs admin panel (and documentation). Want to double check and let me know if it works for you too?