Balsamiq Edit: Option to disable Autosave has been implemented in version 3.4.1
We now save every change you make, as you make it.
Even if you have never saved a project, we actually save it in a semi-hidden folder on your hard drive so that you'll find it when you restart the app.
It seems like a little thing, but it's a real peace of mind once you get used to it.
The only drawback at the moment is that there's no "revert to a previous version" functionality within the app...stay tuned, we are working on bringing the same powerful "project history" features of myBalsamiq to the Desktop as well.
What do you think of this change?