According to Forbes.com:
As of June 10, 2011, the District of Columbia and 22 states imposed estate and/or inheritance taxes. Illinois is the latest of the states to adopt a tax; it acted in January. In May Connecticut lowered the amount it exempts from its tax from $3.5 million to $2 million per estate, retroactive to Jan. 1. (As in the federal system, bequests to a spouse are state-estate-tax-free.)
States with estate taxes typically exempt $1 million or less per estate from their tax and impose a top rate of 16%. Six states levy only an inheritance tax, with the rate depending on the relationship of the heir to the deceased and the taxes kicking in, in some cases, on the first dollar of bequest. Two states, Maryland and New Jersey, impose both. Maryland, for example, imposes an estate tax of up to 16% above a $1 million exemption, and a 10% inheritance tax on every dollar left to a niece, nephew, friend or partner, but no inheritance tax on money left to children, grandchildren, parents or siblings. (Any estate tax owed is reduced by the inheritance tax paid.)
Once again, New England compares unfavorably to the rest of the country. Check out this map at Forbes.com to see how your state matches up.