The real-time collaboration mock ups that Pau created and we presented at Wikimania have a feature which is similar, where you can see who else is currently editing a given page (and be notified when another edit starts) even if you don't choose to start/join a collaborative editing session.
But even if/when that work is implemented, I think there are better ways to handle merging edit conflicts.
The VE model does actually help here some -- the patches I've been working on for VE real-time collaborative editing do provide a way to "transpose" actions w/r/t each other, which allows you to merge two edit histories in some cases. Possibly an early use of this feature might be to allow VE to provide a nicer edit conflict resolution screen, with the option to automatically merge your edits in certain cases. --scott