The purpose of the Aarhus Convention is to make environmental information available to the public. It was approved by the EC in 2005 by Council Decision 2005/370/EC and the text of the Convention as approved by the EC can be found here. The EC had already adopted Directive 2003/4/EC which has the same substantive content as the Aarhus Convention but only applies to the member States.
What was needed was a measure to make the Aarhus Convention apply to the EC institutions and bodies themselves. And that's what Regulation 1367/2006 does. It complements Regulation 1049/2001 on public access to documents.
The Regulation will lead to changes in the rules of procedure of the different institutions and bodies. Those changes should be made by June 28th, 2007, when Regulation 1367/2006 becomes applicable.