Finding

There is no way of knowing if a cell contains conditional formatting without selecting it and displaying the Conditional Formatting dialog box.
You can however use the (Edit > Goto) dialog box and select "Special" to help you identify which cells have conditional formatting associated with them.
Selecting "All" will highlight all the cells on the active worksheet that contain conditional formatting.
Selecting "Same" will only highlight cells on the active worksheet which have the same conditional formatting as the active cell.

In Excel 2002 and Excel 2003 you can use the (Edit > Find) dialog box to locate cells with special formatting.
However this will not identify any cells that have been formatted as a consequence of conditional formatting.