OpenGoo probably doesn't need a super fancy native app that requires objective-C hours and APIs back to each instance you want to access.
The webapp approach seems best. A template and redirect would probably do it. DeviantArt.org still has my favorite implementation of complex web app to iphone.
Some thoughts:
On login: A Dashboard of action items, which features and drills down to priority items
Workspaces would probably be in a Select box, and Functions (Overview, Notes, Contacts, etc. as Lists, which then drill down to action items?
The first thing to do is think about use cases for interaction on the iphone, as OpenGoo presents a lot of different information within it's 3 columns, and one of the biggest challenges will be to make the info accessible within a 1 column view with less real estate.
I'm checking it out, but thoughts?