Twitter has its own official apps for your iPhone, Android, and BlackBerry devices, but there are also a lot of third-party apps that bring their own flavor to your feed. Twitter recently made it harder for those, and popular desktop apps, to access your information, and now it's put the kibosh on UberTwitter and twidroyd completely.
According to a Twitter blog post, the company has suspended both apps for violating its policies but doesn't offer up which policy they have violated. Twitter did mention that its rules put users and the Twitter platform first, so it's possible that UberTwitter and twidroyd's suspension could have something to do with privacy or trademark infringements.
If you're using one of these apps, I recommend using the official Twitter app until further notice, which is exactly what Twitter wants you to do as well.