Eclipse Fails to Load: org.eclipse.swt.SWTException

Eclipse Juno 4.2 inexplicably crashed on me today and then it failed to start again. It was throwing this exception in the .metadata/.log file:
org.eclipse.swt.SWTException: Failed to execute runnable (java.lang.NullPointerException).

Turns out there is a bug logged for this that describes what the problem is, but the quick workaround that is described there is to delete your .metadata/.plugins/org.eclipse.e4.workbench/workbench.xmi file. The only downside to this is that you'll have to rearrange your windows back to how you like them.