There is no "Restore this Version" of a wikipage available, so how do you do it?

The work-around is actually fairly straight forward:

1. On the wikipage that needs to be restored to an earlier version, click on the "Revisions" link in the top right-hand corner
   NOTE: There is a number in front of the word revision, it will look something like this: 251 revisions
   1. A new page will open up with a list of all the previous revisions
2. Find the revision you want to restore and click on it
3. Select all the text on the page (right-click, Select all)
4. Copy it to your clipboard (right-click, Copy)
5. Go back to the page you want to restore
6. Click on "Edit Page"
7. Select all the text on the page (right-click, Select all)
8. Paste contents of Clipboard (right-click, Paste)
9. Write a small message explaining the edit. (Optional)
10. Click "Save Page"

Your wikipage has been restored!