Installed and tested on a multi-site network.
Adds a panel to the lower left rail below Settings: http://imm.io/5zZ4
When click, Pass Expire Settings, shows you a panel of options: http://imm.io/5zZa
Unfortunately, I click reset all and tried to set the expiration for 30 or 60 days and it doesn't save the action. Nothing happened.
There is a filter to see who hasn't been active in so many days, but that's not working either.
I pinged the developer yesterday, but no reply.
Andrea, this would be a most important addition to WordPress. I have 200 users and I don't have the time or luxury to go into every one and change their password. Universities require a password change every 90 days. I'll ping Andre Nacin and mention it to him, but if you could bring this up to the powers that be, I would appreciate it.