There are a lot of people who currently use the Excel Spreadsheet Add-in for Oracle OLAP 10g cubes. Moving to Oracle OLAP 11g cubes, the spreadsheet add-in has been replaced by the MDX Provider for Oracle OLAP. If you need to learn how to use the MDX Provider for Oracle OLAP with Excel spreadsheets, Oracle has now come up with a nice tutorial that covers "how to use Excel 2007 with Oracle11g OLAP data for easy and powerful ad hoc query and analysis":