Why would you use a wiki?
New in Google Docs and Google Sites – Official Google Docs Blog
Earlier this year, we added the ability to “Upload any file” to Google Docs so that you upload, store, and share any file up to 1 GB in size. Now you can upload new versions of the same file to your document list. Previously, each time you updated a file, you would have to upload the new version as a new file with a new URL, re-share it, and put in the correct folders again.
When you select the “Add or manage versions” option on any file, you can upload new versions of a file, download previous versions, and delete older versions.