ISBOLD

ISBOLD(rgeCell)
Returns whether a particular cell has been formatted in bold.

REMARKS
Public Function ISBOLD( _

Public Function ISBOLD( _ 
         ByVal rgeCell As Range) _ 
         As Boolean 

   If (rgeCell.Font.Bold) Then 
      ISBOLD = True 
   End If 
End Function 

Returns TRUE if the cell is bold or FALSE if it isn't.
If you afterwards change the bold setting in the cell, you have to press Ctrl+Alt+F9 to have the formula recalculated.
This function does not recognize formatting if it is applied via conditional formatting.

For instructions on how to add this function to a workbook refer to the page under Inserting Functions