Compostable Bags

Hmm...I'm not sure about large biodegradable shopping bags but for dog clean-up bags, there's BioBag (http://greenhome.huddler.com/products/biobag-compostable-bags) - I'm pretty sure they have bags specifically sized for picking up after your dog.  They also have bags for kitchen, trash and lawn scraps.  I've only used the kitchen ones, which I assume are made of the same material as the rest of them.  They're quite good.  They stretch out a bit if you pack heavy stuff into them and if you leave food scraps, etc. in them for a while, they will leak as I think they are a bit more porous than normal plastic.

Biobag does indeed make a "dog waste"-size bag: http://www.biobagusa.com/biobag_dog.htm#dog.

They also make litter-box liners: http://www.biobagusa.com/biobag_dog.htm#cat.

Considering that the Pooch Pick-up brand only contains 5% biodegradable resin (the rest is plastic), I will be switching to Biobag.