It seems Twitter is suspending third-party applications. Refer this post. Fortune magazine has written an article as "Trouble @ TWitter". Is it worth spending more time/effort on Twitter for marketing the business/products?
I wrote an article about this (specifically about Twitter killing TweetDeck), here: unitedtechguys.com/2011/04/19/twitter-is-going-to-kill-tweetdeck/ Basically, Twitter is tired of all the tools built on its API. There’s nothing necessarily wrong with these tools, but Twitter’s long-term strategy requires all eyes to be focused on official Twitter clients. If the majority of users are using third-party clients, then the majority of users won’t see Twitter ads, promos, or Quickbars. Therefore Twitter loses a lot of potential monetization. Twitter's redesign made it very clear that Twitter wants to take on third-party clients. Now they're likely planning to kill TweetDeck as well.