New is suddenly missing in Project Explorer

Reported at http://in.relation.to/Bloggers/JBossTools31CR1Released#comment14229

Download a clean copy of Galileo SR-1 and start it
Right-click in Project Explorer (Java EE Perspective) - New is present
Install Subclipse (http://subclipse.tigris.org/update_1.6.x) and restart
Right-click in Project Explorer (Java EE Perspective) - New is present
Install BIRT (http://download.eclipse.org/birt/update-site/2.5/) and restart
Right-click in Project Explorer (Java EE Perspective) - New is present
Install Maven (http://m2eclipse.sonatype.org/update-dev) and restart
Right-click in Project Explorer (Java EE Perspective) - New is present
Install JBoss Tools (http://download.jboss.org/jbosstools/updates/development)
Right-click in Project Explorer (Java EE Perspective) - New is now missing