Barack Obama's memo that government officials should confer with the Department of Justice before abiding by any of George W. Bush's signing statements is an adequate first step, but the president should really announce that his administration will not adhere to any of the statements and that the he will not be issuing any such statements.
Instead, Obama said he'd use them sparingly and wisely, but the Constitution allows only one course of action for a chief executive who disagrees with a law passed by Congress -- the veto. While there is limited precedent for signing statements to clarify the application of a newly passed law, there is none at all for reinterpreting or ignoring statutes passed by the legislative branch. The president cannot decide when a law is unconstitutional; that is the work of the courts.
Update: Upon reading Obama's memo I am more satisfied with his policy toward signing statements. The president also made another good move today by overturning the Bush policy on embryonic stem cell research, one of several steps he's taking to end the previous administration's war on science.