In June, Adam Jaques from the Advanced Products Group in Sydney demonstrated the Citrix ICA client on an iPhone. The video is on YouTube and can be seen from here:
Keep in mind that this is just a demonstration. If you see this as a valuable thing, please request it either through your normal channels of communication or fill in the poll below:
The real question is whether or not you want support with the iPhone and Citrix XenDesktop and XenApp.