Increasing the limitation on the unified credit used to determine the Maryland estate tax from the amount corresponding to a $1 million exclusion amount under the federal estate tax to the amount corresponding to a $2 million exclusion amount under the federal estate tax; repealing a requirement that the tax be determined without regard to the deduction for State death taxes under the federal estate tax; stating the General Assembly's intent; applying the Act to decedents dying after December 31, 2005; etc.