The flickering problem, in which the screen intermittently goes black for a few seconds, has been outlined by a number of new 2012 Mac Mini users, who report that it occurs when their systems are connected to HDMI video devices.
This problem seems isolated to HDMI connections and does not affect DisplayPort connections through the Thunderbolt port on the Mac.
Some experiencing this problem have suspected their televisions and display devices to be the root of the problem, but recently Intel has acknowledged that the issue is rooted in its OEM drivers for the HD 4000 graphics embedded in its CPUs. In a posting at its support community, Intel claims the fixed driver has been submitted to Apple and should be available when Apple is able to configure the driver for use with OS X.
We are aware of the flickering issue, and there will be a fix provided in the future. The overall flicker issue is also being addressed here; http://communities.intel.com/thread/32932.
Since for now the problem is limited to HDMI connections, if you have alternative inputs on your display then try using those with your Mac Mini instead. In the latest developer preview update of OS X, Apple is apparently concentrating on graphics drivers and may include the updated Intel drivers when OS X 10.8.3 is released, or may issue a standalone display software update.