During MacWorld, the Citrix guys were there touting the new receiver app. A
PR blurb indicates they plan on releasing it via the AppStore 1Q'09. Additionally, it will be a free download:
"Application delivery firm Citrix has been demonstrating its long-rumoured iPhone client at the Macworld show this week.
Executives confirmed that it would ship through Apple's App Store as a free download this quarter."
(source: Citrix readies iPhone client - vnunet.com)
Personally, I'm looking forward to trying this out. The demos look promising for feature-rich use of the actual Ofc apps.