I tried Google Drive today and promptly noticed that the "organize" feature of Google Docs went from a multi-selectable checkbox (in which you can check multiple collections for a document to be "in"):

To what (appears to be) a single select version:

Personally I loved the flexible concept of document collections. Am I missing something? Is there another view that allows me to have that same document collection support? I realize that you can't have the same file in two folders, but I really didn't expect to loose organizational power/configuration just by giving it a "Try"...