I love this move.
Additions from Nico's "since deleted redundant" post:
One can view the trade from two angles: In a vacuum, is this a good deal for Oakland? In context of a team rebuilding for 2014-15, is this a good deal for Oakland?
Seth Smith's career stats can be found here. Coors Field disclaimers apply. Note that Smith has extreme L/R platoon splits as well as predictable Coors/Not Coors ones.