The current release of the OpenShift Tools isn't compatible with the latest release of EGit, as reported by Eclipse:

Cannot complete the install because of a conflicting dependency.
Software being installed: Eclipse EGit 2.0.0.201206130900-r (org.eclipse.egit.feature.group 2.0.0.201206130900-r)
Software currently installed: JBoss OpenShift Tools 2.3.1.v20120715-0255-H145-Final (org.jboss.tools.openshift.express.feature.feature.group 2.3.1.v20120715-0255-H145-Final)
Only one of the following can be installed at once:
Git Team Provider UI 2.0.0.201206130900-r (org.eclipse.egit.ui 2.0.0.201206130900-r)
Git Team Provider UI 1.1.0.201109151100-r (org.eclipse.egit.ui 1.1.0.201109151100-r)
Git Team Provider UI 1.3.0.201202151440-r (org.eclipse.egit.ui 1.3.0.201202151440-r)
Git Team Provider UI 1.2.0.201112121913 (org.eclipse.egit.ui 1.2.0.201112121913)
Git Team Provider UI 1.0.0.201106090707-r (org.eclipse.egit.ui 1.0.0.201106090707-r)
Cannot satisfy dependency:
From: Eclipse EGit 2.0.0.201206130900-r (org.eclipse.egit.feature.group 2.0.0.201206130900-r)
To: org.eclipse.egit.ui [2.0.0.201206130900-r]
Cannot satisfy dependency:
From: JBoss OpenShift Tools 2.3.1.v20120715-0255-H145-Final (org.jboss.tools.openshift.express.feature.feature.group 2.3.1.v20120715-0255-H145-Final)
To: org.jboss.tools.openshift.express.ui [2.3.1.v20120715-0255-H145-Final]
Cannot satisfy dependency:
From: OpenShift UI 2.3.1.v20120715-0255-H145-Final (org.jboss.tools.openshift.express.ui 2.3.1.v20120715-0255-H145-Final)
To: bundle org.eclipse.egit.ui [1.0.0,2.0.0)

Please advise.