Update (Aug.8/06) - Official Google Blog Post: Saved locations on Google Maps (Thai Tran gives a great use for the "auto-complete" feature in this post)
A new feature has turned up today on Google Maps for registered Google users. When logged into to your Google account you'll notice a new link up along the top of the main Google Maps page labeled: "Saved Locations". This feature will collect and record your searches, then list them for you to return to later. Saved searches are listed in order by clicking the Saved Locations link. You can label or delete each previous search or add a new location. You can also turn the feature off by un-checking "Enable auto-saving of locations". This feature is quite handy if you're searching many locations and don't wish to keep retyping the request or continually select from your Bookmarks or Favorites folder.. A nice addition.