The good new is it works already. Just be sure to click on the T in the top left corner of the keyboard. ( the default is A for alternate keyboard .. function keys etc ) This will promt a local keyboard buffer that allows you to see and edit the text input which can be entered by normal keystroke… or the new Siri Dictation feature of the new iPad. Then press send to insert the text into the app running on Citrix XenDesktop/XenApp. First be sure to first have the cursor in the desired text field in the app.
BTW, this also works with the iPhone 4S.
Try it out !