Having extensive knowledge regarding the estate tax I thought I should chime in.
There currently is no death tax. However, Congress may still pass a death tax and according to the Supreme Court, taxes may be applied retroactively going back at least a year (anything longer than a year is suspect). So just because there is no death tax right now does not mean that George's family won't have to pay taxes.
In fact, next years death tax exemption will be $1 million with a 55% tax rate over a million (you also get a full marital deduction meaning you can pass everything to your spouse without paying taxes however upon the surviving spouses death taxes will be paid). Congress is not happy about this. Democrats want to raise the exemption to $3.5 million (what it was in 2009) while Republicans want to raise it to $5 million. Chances are such legislation will be passed by the end of the year and will be applied retroactively to 1/1/2010.
There is a very good change that George's family will in fact pay the death tax. Think about it, with more than 3 billionares having died this year, and given the current financial situation, Congress will do everything it can to take half of these billionares estates.
Assuming that no law is passed, whether his family will pay estate taxes will depend on his estate plan. It is very possible that his estate plan called for the majority of his assets to be passed to his wive that way the marital deduction would apply. If this is true then the wife will get hit with the estate tax upon her death regardless of the tax rate today.