While Gmail users can already set their status, each update overwrites the previous message. Google plans to extend this feature, allowing Gmail users to view a stream of status updates from people they choose to connect with. It will also be tightly integrated with YouTube and Picasa, Google's video and image-sharing services.
Yahoo introduced a similar "status-casting" feature last year, which allows users read their contacts' 140-character updates via Yahoo Mail or Messenger, as well as Flickr, Twitter and others. It's unclear whether Google will link Gmail status updates to rival social-networking services, but it seems like it would be beneficial.