It is recommended to upgrade to the latest official version of RadControls for ASP.NET AJAX Q1 2011 (version 2011.1.315) where RadEditor offers support for iPad.
If you use an older version, you can also review our KB article on iPhone/iPad compatibility at http://www.telerik.com/support/kb/aspnet-ajax/editor/support-for-iphone-browser.aspx
Please note that at the moment it is not possible to use the rich text editing features of the RadEditor on an iPhone/iPad
browser. The mobile Safari browsers do not support the contenteditable attribute and will not show the keyboard when you tap inside a contenteditable element. For this reason the editor is rendered as a standard textarea element on an iPhone/iPad
We hope that a future version of the mobile Safari browser will support the contenteditable attribute and rich text editors like RadEditor will be usable on the Apple mobile platform.
the Telerik team