In the trunk version (6553), the command "mvn install" with JDK 1.4.2 ends with that message :
[INFO] ------------------------------------------------------------------------
[ERROR] BUILD ERROR
[INFO] ------------------------------------------------------------------------
[INFO] Internal error in the plugin manager executing goal 'info.magnolia:maven-setproperty-plugin:1.0-SNAPSHOT:set-property': Unable to find the mojo 'info.magnolia:maven-setproperty-plugin:1.0-SNAPSHOT:set-property' in the plugin 'info.magnolia:maven-setproperty-plugin'
info/magnolia/maven/setproperty/SetPropertyMojo (Unsupported major.minor version 49.0)

I think the maven-setproperty-plugin has been compiled with JDK 5.0 and not with backwards compatibility on JDK 1.4

Here is the complete log for the command :
C:\Developpements\Java\Projets\magnolia-svn>mvn clean install
[INFO] Scanning for projects...
[INFO] Reactor build order:
[INFO] magnolia-project
[INFO] magnolia-core
[INFO] magnolia-jaas
[INFO] magnolia-module-cache
[INFO] magnolia-exchange-simple
[INFO] magnolia-gui
[INFO] magnolia-module-admininterface
[INFO] magnolia-module-mail
[INFO] magnolia-module-templating
[INFO] magnolia-module-workflow
[INFO] magnolia DMS
[INFO] magnolia-taglib-cms
[INFO] magnolia-taglib-utility
[INFO] magnolia-editor-fckeditor
[INFO] magnolia-editor-kupu
[INFO] magnolia
[INFO] ----------------------------------------------------------------------------
[INFO] Building magnolia-project
[INFO] task-segment: [clean, install]
[INFO] ----------------------------------------------------------------------------
[INFO] [clean:clean]
[INFO] Deleting directory C:\Developpements\Java\Projets\magnolia-svn\target
[INFO] Deleting directory C:\Developpements\Java\Projets\magnolia-svn\target\classes
[INFO] Deleting directory C:\Developpements\Java\Projets\magnolia-svn\target\test-classes
-----------------------------------------------------
this realm = app0.child-container[info.magnolia:maven-setproperty-plugin]
urls[0] = file:/C:/Documents and Settings/aogier/.m2/repository/info/magnolia/maven-setproperty-plugin/1.0-SNAPSHOT/maven-setproperty-plugin-1.0-SNAPSHOT.jar
urls[1] = file:/C:/Documents and Settings/aogier/.m2/repository/commons-lang/commons-lang/2.1/commons-lang-2.1.jar
Number of imports: 0

this realm = plexus.core.maven
urls[0] = file:/C:/Developpements/Java/APIs/maven-2.0.4/bin/../lib/commons-cli-1.0.jar
urls[1] = file:/C:/Developpements/Java/APIs/maven-2.0.4/bin/../lib/doxia-sink-api-1.0-alpha-7.jar
urls[2] = file:/C:/Developpements/Java/APIs/maven-2.0.4/bin/../lib/jsch-0.1.24.jar
urls[3] = file:/C:/Developpements/Java/APIs/maven-2.0.4/bin/../lib/maven-artifact-2.0.4.jar
urls[4] = file:/C:/Developpements/Java/APIs/maven-2.0.4/bin/../lib/maven-artifact-manager-2.0.4.jar
urls[5] = file:/C:/Developpements/Java/APIs/maven-2.0.4/bin/../lib/maven-core-2.0.4.jar
urls[6] = file:/C:/Developpements/Java/APIs/maven-2.0.4/bin/../lib/maven-error-diagnostics-2.0.4.jar
urls[7] = file:/C:/Developpements/Java/APIs/maven-2.0.4/bin/../lib/maven-model-2.0.4.jar
urls[8] = file:/C:/Developpements/Java/APIs/maven-2.0.4/bin/../lib/maven-monitor-2.0.4.jar
urls[9] = file:/C:/Developpements/Java/APIs/maven-2.0.4/bin/../lib/maven-plugin-api-2.0.4.jar
urls[10] = file:/C:/Developpements/Java/APIs/maven-2.0.4/bin/../lib/maven-plugin-descriptor-2.0.4.jar
urls[11] = file:/C:/Developpements/Java/APIs/maven-2.0.4/bin/../lib/maven-plugin-parameter-documenter-2.0.4.jar
urls[12] = file:/C:/Developpements/Java/APIs/maven-2.0.4/bin/../lib/maven-plugin-registry-2.0.4.jar
urls[13] = file:/C:/Developpements/Java/APIs/maven-2.0.4/bin/../lib/maven-profile-2.0.4.jar
urls[14] = file:/C:/Developpements/Java/APIs/maven-2.0.4/bin/../lib/maven-project-2.0.4.jar
urls[15] = file:/C:/Developpements/Java/APIs/maven-2.0.4/bin/../lib/maven-reporting-api-2.0.4.jar
urls[16] = file:/C:/Developpements/Java/APIs/maven-2.0.4/bin/../lib/maven-repository-metadata-2.0.4.jar
urls[17] = file:/C:/Developpements/Java/APIs/maven-2.0.4/bin/../lib/maven-settings-2.0.4.jar
urls[18] = file:/C:/Developpements/Java/APIs/maven-2.0.4/bin/../lib/plexus-interactivity-api-1.0-alpha-4.jar
urls[19] = file:/C:/Developpements/Java/APIs/maven-2.0.4/bin/../lib/wagon-file-1.0-alpha-7.jar
urls[20] = file:/C:/Developpements/Java/APIs/maven-2.0.4/bin/../lib/wagon-http-lightweight-1.0-alpha-6.jar
urls[21] = file:/C:/Developpements/Java/APIs/maven-2.0.4/bin/../lib/wagon-provider-api-1.0-alpha-6.jar
urls[22] = file:/C:/Developpements/Java/APIs/maven-2.0.4/bin/../lib/wagon-ssh-1.0-alpha-7.jar
urls[23] = file:/C:/Developpements/Java/APIs/maven-2.0.4/bin/../lib/wagon-ssh-external-1.0-alpha-6.jar
Number of imports: 0

this realm = plexus.core
urls[0] = file:/C:/Developpements/Java/APIs/maven-2.0.4/bin/../core/plexus-container-default-1.0-alpha-9.jar
urls[1] = file:/C:/Developpements/Java/APIs/maven-2.0.4/bin/../core/plexus-utils-1.1.jar
Number of imports: 0
-----------------------------------------------------
[INFO] ------------------------------------------------------------------------
[ERROR] BUILD ERROR
[INFO] ------------------------------------------------------------------------
[INFO] Internal error in the plugin manager executing goal 'info.magnolia:maven-setproperty-plugin:1.0-SNAPSHOT:set-property': Unable to find the mojo 'info.magnolia:maven-setproperty-plugin:1.0-SNAPSHOT:set-property' in the plugin 'info.magnolia:maven-setproperty-plugin'
info/magnolia/maven/setproperty/SetPropertyMojo (Unsupported major.minor version 49.0)
[INFO] ------------------------------------------------------------------------
[INFO] For more information, run Maven with the -e switch
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 1 second
[INFO] Finished at: Wed Oct 04 12:58:40 CEST 2006
[INFO] Final Memory: 6M/12M
[INFO] ------------------------------------------------------------------------