This was mentioned, but I thought it bore repeats: styrofoam is almost all air. There' actually very little material in it, and that really lowers it's environmental impact. It's not so terrible. Aside from being reusable almost indefinately (also mentioned by the foam reseller) which is much better than recycling, it can be melted down before being trashed and it takes up a tiny percentage of its original volume.
It's incredibly handy and good at what it's for, so I'm going to say I'm a fan.