Not directly but a few things have been added to 2.3
ArcGIS.Desktop.Editing.Events.EditCompletingEvent is the equivalent OnBeforeStopOperation
ArcGIS.Desktop.Core.Project.EditedDatastores returns the data stores (workspaces) that have pending edits which have not been saved.
ArcGIS.Desktop.Editing.Events.EditCompletedType now includes post and reconcile.
The OnStopEditing equivalent would be the EditCompleted event where the EditCompletedType would be either save or discard. Both of these stop the edit session. EditCompletedEventArgs provides the changes during an individual editoperation. Additionally the rowevents will also fire during the operation.
There's no equivalent for OnStartEditing. An editoperation will start an edit session if there isnt one already going during Execute but it wont know whats changed until its completed.
The IDataChanges equivalent is in progress.
Conflict support is currently limited.