There’s a short article on Law.com’s Legal Technology page, “Covering the Bases of Electronic Discovery” by Michael A. Gold, that might prove to be a useful introduction to the U.S. situation and, therefore, to the complexities of e-discovery generally.
The last word from Gold:
As in-house lawyers become more savvy about e-discovery under the new rules, outside lawyers will not be able to fake the level of expertise their corporate clients will come to routinely expect. Even a longstanding relationship with the client will not remain stable very long if outside counsel cannot convince a general counsel that his back is covered when it comes to e-discovery.