TweetDeck, who was acquired by Twitter a while back, will be discontinuing a lot of its native and quasi-native apps, including Tweetdeck iOS and Android, and its Air app for Mac. If you use TweetDeck on the web, those tools will still remain, and that's where they'll choose to focus their energies and development going forward. According to the TweetDeck blog:
To that end, we are discontinuing support for our older apps: TweetDeck AIR, TweetDeck for Android and TweetDeck for iPhone. They will be removed from their respective app stores in early May and will stop functioning shortly thereafter. We’ll also discontinue support for our Facebook integration.
Anyone who has ever used AIR for Mac may actually be glad it's finally getting put out of its misery. Unfortunately, Twitter for Mac being kept alive. Torturously.
TweetDeck on the web has always been a better experience and will continue to be developed, including plugins for browsers such as Google Chrome.
The real question is, if you still use TweetDeck for iOS or AIR on your Mac, will the web version be enough for you?