Their tools aim to make development faster and easier, and already support some of the new APIs in Mango.
Some of their controls include:
Telerik is also offering a 60 day free trial, helping developers decide if the time saving of using the controls is worth the cost of the software. The company is currently running a sale, offering the controls for only $99, down from the regular $399 to $499, but this will only last another 8 days,
Read more about the package at Telerik here.