I have a column containing a sorted list of values which includes duplicate
values such as:

Row 1: 1
Row 2: 1
Row 3: 2
Row 4: 3
Row 5: 3
Row 6: 4
Row 7: 4
Row 8: 4
Row 9: 5

Without using VBA or macros (an unfortunately non-negotiable requirement of
the customer) I'm tasked to do the following using conditional formatting:
1. Make a cell that has the same value as the cell immediately above it the
same color as that of the cell immediately above it
2. Make the color of a cell whose value is not the same as the cell
immediately above it a different color than the cell immediately above it
3. Alternating two colors is fine

For my example data, the cells in rows 1 and 2 should be yellow, row 3
should be blue, row 4 and 5 should be yellow, row 6 through 8 should be
blue, and row 9 should be yellow.

Using Excel 2003 and just formulas, I don't think that this is possible but
I'm hoping that someone out there will know better. I don't know if Excel
2007 has added something to make this possible.

Anyone know of a way to do this?

Brian