Hi Koko,
All depends really on what the different people will be accessing really.
If for instance you had one person who will only be creating the templates, one person who will be doing the data entry and so on and so forth then you can lock down the admin panel to only let them have access to the certain areas they need. That way then you should never have any problems.
If on the other hand though you had more than one person working on say the template side of things then I can definitely see where this could get really interesting 
Not really something that I should think you would want anyway though because why would you have more than one person working on the same thing at the same time? That would be a little akin to two builders working on the same part of a structure but not knowing about the other person. Both turn up one day to place their part of the building up and find another person there trying to do the same thing.
Really it’s best to delegate parts of a sites development to certain people wherever you can so that this sort of thing doesn’t happen. A good game plan can get this sorted out quite easily.
There is however an extension called Occupied which I’m pretty certain still works fine with 1.6.7 which will alert you if you try to open an entry, template or wiki entry which someone else is already working with which may well help out quite a bit in this situation.
There is also NSM Publish Plus a paid offering which helps with versioning for weblog entries and complete workflow within them too which might help out too.
Hope some of that helps a bit.
Best wishes,
Mark