I tried to upload the Jboss parent to see if the problem is coming from GateIn but it doesn't. I have the same one :
arnaud@mbp-arnaud:~/Projets/JBoss/Code/jboss-parent-pom-trunk$ mvn deploy
[INFO] Scanning for projects...
[INFO] ------------------------------------------------------------------------
[INFO] Building JBoss Parent POM
[INFO] task-segment: [deploy]
[INFO] ------------------------------------------------------------------------
[INFO] [enforcer:enforce {execution: enforce-plugin-versions}]
[INFO] [site:attach-descriptor {execution: default-attach-descriptor}]
[INFO] [source:jar-no-fork {execution: attach-sources}]
[INFO] [install:install {execution: default-install}]
[INFO] Installing /Users/arnaud/Projets/JBoss/Code/jboss-parent-pom-trunk/pom.xml to /Users/arnaud/.m2/repository/org/jboss/jboss-parent/5-beta-3-SNAPSHOT/jboss-parent-5-beta-3-SNAPSHOT.pom
[INFO] [deploy:deploy {execution: default-deploy}]
[INFO] Retrieving previous build number from jboss-snapshots
[WARNING] *** CHECKSUM FAILED - Checksum failed on download: local = '6e401588cbf67812b286c0b363cb70ae05aea31c'; remote = 'cac90530f3cd25c1b199b774ce67ad17f4ba3dba' - RETRYING
[WARNING] *** CHECKSUM FAILED - Checksum failed on download: local = '6e401588cbf67812b286c0b363cb70ae05aea31c'; remote = 'cac90530f3cd25c1b199b774ce67ad17f4ba3dba' - IGNORING
11K uploaded (jboss-parent-5-beta-3-20091002.230227-3.pom)
[INFO] Retrieving previous metadata from jboss-snapshots
[WARNING] *** CHECKSUM FAILED - Checksum failed on download: local = '976bbb599a114b7e28418b351e17ca927e70ab1c'; remote = '6ccc6f14924a501d867c93fb7bd3fd006e31da51' - RETRYING
[WARNING] *** CHECKSUM FAILED - Checksum failed on download: local = '976bbb599a114b7e28418b351e17ca927e70ab1c'; remote = '6ccc6f14924a501d867c93fb7bd3fd006e31da51' - IGNORING
[INFO] Uploading repository metadata for: 'artifact org.jboss:jboss-parent'
[INFO] Retrieving previous metadata from jboss-snapshots
[WARNING] *** CHECKSUM FAILED - Checksum failed on download: local = '6e401588cbf67812b286c0b363cb70ae05aea31c'; remote = 'cac90530f3cd25c1b199b774ce67ad17f4ba3dba' - RETRYING
[WARNING] *** CHECKSUM FAILED - Checksum failed on download: local = '6e401588cbf67812b286c0b363cb70ae05aea31c'; remote = 'cac90530f3cd25c1b199b774ce67ad17f4ba3dba' - IGNORING
[INFO] Uploading repository metadata for: 'snapshot org.jboss:jboss-parent:5-beta-3-SNAPSHOT'
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESSFUL
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 38 seconds
[INFO] Finished at: Sat Oct 03 01:03:02 CEST 2009
[INFO] Final Memory: 27M/125M
[INFO] ------------------------------------------------------------------------