Storing file revisions is quite resource intensive and may not always be
desired. I've changed it from being an always-on feature to something that has to be
enabled in site settings.
Site -> Edit Site -> Advanced -> Save file revisions.
You can then access revisions from:
File -> Revision History
Because it's a more resource intensive feature it will become a Premier only feature.
I will also change the number of sites available in free edition from 3 to 1. The reason for this is to increase revenue so that I can invest more time in development. At the moment I don't think there is enough incentive to upgrade and premier users account for < 0.5% of total users.
These changes will come into affect September 8th.
This follows on the from the mailing list discussion.