I am afraid the implementation of Chart Annotations is still not scheduled, however we realize the importance of such feature and it is in our ToDo list. Actually this idea
has been already shared at our UserVoice page, so if you wish you may cast a vote for it. The more votes it collects, the higher priority will have.
the Telerik team
Join us on our journey to create the world's most complete HTML 5 UI Framework - download Kendo UI