Hey, There's been some discussion for a while about having a common logical plan format for Pig and Hive to pass to their physical plan generators. Erik Meijer gave a talk recently on LINQ Expression Trees that made me think they would serve as an excellent intermediate data structure. You can read more about them here: http://msdn.microsoft.com/en-us/library/bb882636.aspx, and you can read the proposal for Erik's presentation here [PDF]: http://research.microsoft.com/~emeijer/Papers/Cloud%20computing%20workshop%20proposal%20Draft.pdf.
I was planning to save this discussion for a time when I understood the plan structures in both Pig and Hive, but given the discussion around Hive future plans going on right now, I figured now's as good a time as any to get it started. Later, Jeff
