Determine the row number of an unformatted row in views
Views already wraps each row in all sorts of CSS classes, like views-row, views-row-#, views-row-first, views-row-last, etc, so if all you want to do is STYLE things differently, you can use these classes.  Now, if you want to re-arrange the CONTENT of your node, that's a whole 'nother story...