Use Version 1 for OG 1.x. There is no node access control now, but you can use Rules to bind state transitions e.g. to publish/unpublish actions.
Version 2 integrates with OG 2.x and is not compatible with OG 1.x. Additionally, it now also integrates with og_access (part of OG). That means that private entries in groups are respected and people cannot view them even if workflow would allow them (enable strict access control in OG settings).
The newest feature is the integration with the Workflow Access module, part of the Worfklow module, which allows to assign node permissions to roles based on the state a node is in. The "Organic Groups Workflow Access" sub-module allows to do the same with group roles. Access to nodes in a group is granted based in the roles of that group.
The latest 7.x-2.x-dev works only with workflow 7.x-1.1-beta3 and 7.x-1.x-dev, because workflow_admin_ui module has been greatly overhauled.
The 6.x version of OG Workflow is no longer maintained.
- Organic Groups
- OG moderation (If you just want simple OG groups role based access control for publishing options and revision of group content.)