I think it's a bit different of a publish/unpublish functionnality.
The files (mainly doc, excel, pdf) are not unpublished in this case, but marked as :
"someone is blocking the file because he's going to update it, so just download it at the moment for consulting it, please don't add anything else till this file is marked as unlocked or updated"
But it needs 2 new proper functionnaliy :
The lock/unlock feature, which is a simple alert I guess :
1.A user is blocking the file ( by clicking a button "block" near download, delete etc...)
2.The name of this user and the date/hour of beginning of blocking is added under the file.
3.A mail (optional , like other tabs of GroupJive) is sended to all members of this group saying : "user x as blocked file x at this time".
4.After the user as updated the doc file locally, he may unlock it : mail sended to say, "user x as unlock the file : be carefull, it has not been updated at this time!" and under the file the mention is "last unlock date : 13/02/2012 16h57" )
Administrator/moderators of this group should unblock an abusively locked files (or forgotten locked...)
But he may also click on "update current file" which leads to the proper 2nd functionnality, meaning that the file can be updated, and a message is sended to all users of that group "user x as updated file x at 13/02/2012 16h57".
The lock/unlock is to alert someone is working on the file, the unlock feature is there in case there was an error with locking it, or if finally there was no modifications (for instance, due to a phone call saying something else to do finally...)
Normaly a user that have locked the file and really modified it should use directly "update the file".
In this case, the updated file should be marked automaticaly as non locked. (because it has just been updated...)
I think that's all...
Thanks !