The 4.1 build failed, somewhere in the provisioning step:
http://build.eclipse.org/eclipse/e4/aioob.txt[p2.director] Installing org.eclipse.sdk.ide 4.1.0.I20110306-2030.
[p2.director] Installing org.eclipse.sdk.ide 4.1.0.I20110306-2030.
[p2.director] Installing org.eclipse.sdk.ide 4.1.0.I20110306-2030.
[p2.director] Installing org.eclipse.sdk.ide 4.1.0.I20110306-2030.
[p2.director] Installation failed.
[p2.director] An error occurred during the org.eclipse.equinox.internal.p2.engine.phases.CheckTrust phase.
[p2.director] session context was:(profile="" phase=org.eclipse.equinox.internal.p2.engine.phases.CheckTrust, operand=, action="">[p2.director] String index out of range: 39913
[p2.director] An error occurred during the org.eclipse.equinox.internal.p2.engine.phases.CheckTrust phase.
[p2.director] session context was:(profile="" phase=org.eclipse.equinox.internal.p2.engine.phases.CheckTrust, operand=, action="">[p2.director] String index out of range: 39913
[p2.director] Operation completed in 161550 ms.
A problem occured while invoking the director.