If you have fewer than 500 employees and you didn't take advantage of Maryland's last amnesty offer back in 2001, then you might want to participate in this program.
It doesn't start til September 1, 2009 but everything must be done by October 30, 2009. Here's the details from CCH:
Maryland Gov. Martin O'Malley has signed legislation that provides an amnesty period from September 1 through October 30, 2009, for taxpayers who failed to file a return or pay personal income, corporate income, withholding, sales and use, or admissions and amusement taxes. The comptroller will waive civil penalties (except previously assessed fraud penalties) and half the interest due if a taxpayer files all delinquent returns and pays all tax and half the interest due, or enters into an agreement with the comptroller, during the amnesty period. Amnesty is not available to taxpayers who have more than 500 U.S. employees, who participated in the 2001 Maryland amnesty program, or who were eligible for the 2004 Delaware holding company settlement period. Taxpayers cannot be charged with a criminal tax offense arising out of any return filed or tax paid during the amnesty period, but amnesty does not apply to criminal charges that are already pending or under investigation.