DragonOne released an updated version of PleaseSleep that is compatible with OS X Mountain Lion, and yes it is still free. PleaseSleep was originally designed for actual Macs, but has proven to be an extremely handy piece of software for CustoMacs too.

If you're not familiar, "PleaseSleep is a utility software designed for Mac OS X that helps put your computer to sleep when you know some other app is preventing your Mac from going to sleep." It also helps to solve several of the reasons why a CustoMac won’t go to sleep, although it can’t solve any hardware related issues that prevent sleep.

"PleaseSleep sits in the background and waits for the sleep timer you set in Energy Saver preferences pane. Depending on the preferences you set, PleaseSleep will try to put your computer to sleep when the scheduled sleep timer kicks in. PleaseSleep is very easy to configure, you can enable, disable, and access its preferences via the system menu bar icon. You can choose to have PleaseSleep activate the sleep function all the time, or you can tell PleaseSleep to activate the sleep function only when certain apps are running."

If you're like me and like to have your system sleep whenever it's not being used, this is the perfect utility app that will basically force sleep your system based on your energy saver settings. You can download PleaseSleep from the source link below.

Source: 
DragonOne PleaseSleep