Emailchemy’s Google Apps Uploader tool gives you the option of selecting a few different kinds of automatic labeling. If you select “Full Hierarchy”, then the entire folder hierarchy (path) will become a label. Gmail uses these labels for faking IMAP folders to an IMAP client. The other is to select “Each Subfolder”, which will break apart the path string into individual labels, so “/2004/work/project_x” will become 3 separate labels: “2004”, “work”, and “project_x”.
Which to use? I like both. That way, you get to preserve the original hierarchy and still have the flexibility of “tags”.