How can I keep Java 7 up to date? As far as I understood Apple provides only Java 6 for Mountain Lion.

Here I found how to install and use Java 7.

However I suppose that by installing Oracle Java it will not be update by means of the Mac App Store. How can I be sure that Oracle Java is always up to date, even better automatically (at least with a notification of "ready to update")?
You may not have noticed it, but Oracle Java 7 installs a new item in System Preferences with a feature that automatically checks for updates by default, and prompts you to install them. Thus, this is taken care of.