The maximum tax bracket or schedule amount would be at 35%. Go to the IRS.gov web site and use the search box for 2009 federal tax rate schedules go to page 13 Click on the below Related Link
Since deductions and credits (and rates) seem to have an uneven effect, the rate any taxpayer pays on say the first $1 is not the same on the first $1 after $10 mill. The first $ is really not taxed...
The general rule is: 45%, but there is much more. The U.S. Federal tax rates for gifts are on the same tax rate schedule as the estate tax. If the gift is a "present interest" gift (they can use it...