>>627
Sub test1()
　Dim rg1 As Range, rg2 As Range
　For Each rg1 In Selection.Areas
　　If rg2 Is Nothing Then
　　　Set rg2 = rg1
　　Else
　　　Set rg2 = Range(rg2, rg1)
　　End If
　Next rg1
　Debug.Print WorksheetFunction.Sum(rg2)
End Sub

>>628
Unionは無理じゃない？