While investigating Bisphenol A and trying to figure out what bottles I owned contained it, I came across an article on the seven resin identification codes (or "recycling codes") put on the bottom of plastic containers. I had always assumed that if a container had the recycling symbol on the bottom that it was recyclable. As it turns out, that's not always the case.
Resin code 7, even though it is commonly drawn as a 7 within the chasing-arrows recycling symbol, is never actually recycled and ends up in the landfill. Code 7 means "other plastic", which means its not one of the typically found 1-6 plastics, or its a combination of plastics.
And even though resin codes 3-6 are recyclable, not all municipalities will recycle them. Check with your local recycling authority to see if they accept products with resin codes 3-6. But even if they do, according to this article, they might not actually do anything productive with it--they might just be putting them in a separate pile until they figure out what to do with them.
The only guaranteed guilt-free plastics you can buy right now are ones with resin codes 1 and 2. So next time you're in the store and looking at a plastic product, check the bottom. Give preference to products using type 1 and type 2 plastics, and definitely do not buy type 7 plastics.