Here's a link to a brilliant article written by Darwin Wiggett and Samantha Chrysanthou on Naturephotographers.net online magazine/forum:
Photoshop and Nature Photography: How Far is Too Far?
Entertaining and thought-provoking, they tackle the great debate between the "Purists" and "Processors". Their photos are, of course, excellent too. Kudos to Darwin and Samantha for hitting this one bang on!