I'm running standard-1.1.2.jar in Tomcat 5.5. Profiling reveals large memory usage in org.apache.jasper.runtime.BodyContentImpl objects. I believe this is because org.apache.taglibs.standard.tag.common.fmt.BundleTagSupport does not call super.release() from it's release() method. The superclass, BodyTagSupport, nulls the reference to bodyContent in it's release() method. The BundleTag instances are pooled by the container, so in between requests the most recent bodyContent cannot be garbage collected. It will be reset on the next startTag() invocation, so the tag behavior is correct, but the memory usage is much higher than it should be.
Sounds plausible. If you add the call to super.release() does the memory usage improve?
Verified and fixed in trunk with r1006320.