Their new Garden Collection features pieces made from recycled materials. The clothing is made from organic cotton, linen and recycled polyester (which is actually made in part from plastic bottles).
From what I've seen, the collection is gorgeous and the pieces look normal, if that makes sense. What I mean to say is that they don't have a hippie-hemp-overly-obvious-recycled-ness look to them.
The dress pictured is made completely from recycled polyester, and I think it's totally chic (the $40 price tag doesn't hurt either).
To find out more about the collection and to find H&M stores, visit their website.