Hi,
The activiti-engine integration is planned to be merged to alfresco-head by the beginning of february, it's currently being developed in a separate branch. This will only include the engine itself, implementing a component used in the WorkflowService.
Currently, we're evaluating what activiti-tools will make sense to use on the activiti-engine inside alfresco, but no concrete plans on how what the packaging/shipping/distribution strategy will be.