"Version 7.2.0.0 - (5-30-13)
•NEW: Tracking Aura added to Goggles. Tracks all player movement over that last 30 minutes, even other players. Used new block ID ("block.hidden"), disabling this block will essentially disable the Tracking Aura."

This Block has some Issues:

• It blocks Piston moving
• Prevents the activation of a Netherportal
• It affects fences. Fences are transformed, as if next to solid-blocks
• It is shown on 'Rei's Minimap'
• Where can I turn off aura tracking? I have found no option in the config

Update Forge to fix most of those issues.

Set block.hidden=0 to turn it off.