OPC - the Open Packaging Conventions - is a recently approved standard for packaging data into a single, compact file. Many people, myself included, have had to create file structures in the past to maintain data in a single file; this creates a packaging standard for creating file structures in a discoverable fashion.

The coolest part about the whole thing is there is an API surrounding it in the .NET framework 3.0 - that is enough of a reason, alone, to be curious about it. It leverages ZIP as the compression format, uses a relational hierarchy for the contained parts and, like I said earlier, supports the concept of discoverability.

Check out this MSDN entry for more if you're curious about what this might provide for you: http://msdn.microsoft.com/msdnmag/issues/07/08/OPC/default.aspx.