commons-logging-1.1 from the migrated-java-experimental-overlay (and probably most versions before) fail to build the classes required to use commons-logging with log4j. The build.xml expects two properties, "log4j12.jar=..." and "log4j13.jar=..." (for log4j versions 1.2* and 1.3* respectively), but the ebuild only sets "log4j.jar=..." which obviously has no effect. Changing the property that gets set to "log4j12.jar=..." works for the moment, since there are no 1.3 ebuilds around so far, but a nicer solution would be to check the existing version(s) and set one or both of the properties accordingly.
Corrected in overlay. Thank you.
Looks good (commons-logging-1.1-r1), marking as fixed, thanks for reporting. The 1.0.4 versions in portage are fine with log4j.jar, the versioned variables were probably introduced only in 1.1 and overlooked.