Ever since Sarbanes-Oxley legislation was passed, auditing firms and their corporate clients have been trying to figure out the standard of proof required for the testing of internal controls.  As you might expect, auditing firms like to play it safe.  Consequently, they have used the ambiguity of Auditing Standard #2, which requires the testing of internal controls, to require a high standard of proof before they were willing to sign off on management's opinion of internal controls.  Clients, on the other hand, have an interest in keeping compliance costs as low as possible.  This sets up a natural conflict between clients and their auditors.

Apparently the PCAOB has gotten the message.  They're looking at ways to reduce the compliance effort while still assessing the strength of key controls.  An article at CFO.com entitled Under Fire: Auditing Standard No. 2 has the details. 

Here's an excerpt from the article:

PCAOB board member Daniel Goelzer, who spoke at a meeting of the National Association of Corporate Directors in Minneapolis on April 27, said the PCAOB will focus on uncovering control weaknesses that are likely to lead to material misstatements rather than matters that are trivial, he said. "That may well require amending AS No. 2." Goelzer did not describe how the auditing standard could be changed, but he stated that the PCAOB will be more aggressive in ensuring that audits of internal controls by outside auditors are performed efficiently.