Twitter announced today a major design overhaul of its Web platform, as well as its mobile apps for iPhone and Android. The TweetDeck client, owned by Twitter, will also be redesigned to match the look of the other platforms. The design changes, which will be rolled out over the next several weeks, include a renovation of user profiles and the dashboard.

As part of the design changes, Twitter has added three new navigation buttons: Home, Connect and Discover. Home takes users to their dashboard, where they can read incoming tweets. Connect shows you all tweets that mention you, retweets of your tweets and tweets of yours that others have favorited. And Discover, which shows you stories, photos, videos, follow recommendations, and trending hashtags based upon your location, language and who you follow.

With the new Twitter dashboard design, Tweets will now appear on the right side of the screen, and take up less of the page than they did with the previous design. The new tweet box will now appear in the same box, now located on the left, which houses you profile picture, and your follow, followers and lists stats. A new Tweet button also appears in the toolbar at the top of the page, making it easier to post a new tweet, even if you aren’t on your dashboard.

The mobile app has the Home, Connect and Discover buttons, as well as a Me button, which shows your profile picture and stats, as well as access to your direct messages and settings.

The website design is currently being rolled out to all users, so you may have to wait a while to see the changes. The redesigned iPhone (iTunes link) and Android (Android Market link) are available right now.

Check out the new design in this video below: