I have had some questions about how exactly this works and what the ramifications are. I've put together a little screen capture that demonstrates the problem in detail. We have tested this with both Snow Leopard Server and Lion Server. Watch this video and you will see exactly what the problem is:
Lion Dataloss on Servers
What needs to happen is that Apple needs to change the API for versions to disable the functionality entirely on shared volumes. With it disabled the app would have to revert back to the "you have unsaved changes, save or quit" behavior of all prior versions of MacOS.
I recognize that Apple is trying to make things easier for the novice, but at the same time the ability to do non-destructive edits is something that people use on the mac all the time. It is a fundamental feature of a computer. What versions is doing is removing the ability for the user to control when they write changes to a document. With a personal system this isn't the end of the world because versions allows you to "revert to save" but with networked volumes this will only end in tears.
If you require that the user first duplicate the document, there will quickly be thousands of duplicate documents on the server that users did not throw away. This is also a big problem.
There has to be an answer to this, and it's going to have to come from Apple.