At a contentious Financial Services Committee hearing today about the failure of the Securities and Exchange Commission to prevent the Bernie Madoff scandal, the SEC's General Counsel cited executive privilege as reason that he and the SEC's enforcement branch were refusing to answer congressional inquiries. You can watch the video here - the executive privilege issue comes at about 5 minutes and 15 seconds into the clip.
As you'll see, SEC officials refuse to answer the committee's basic questions about the Madoff scandal, and the agency's acting general counsel, Andy Vollmer (a Bush holdover and maxed-out donor to John McCain's presidential campaign) explicitly cites executive privilege as his legal rationale for refusing to provide basic information to federal lawmakers.
Congress has a constitutional obligation to engage in basic fact finding, both in order to legislate reforms at the SEC and to publicly expose how our economy was destroyed by sharks like Madoff. Now, Bush holdovers at the SEC are using executive powers - powers that are now President Obama's - to prevent Democratic lawmakers from doing their job.