For some reason, the mobile version of Google Calendar (calendar.google.com on your iPhone) doesn’t allow you to login to Google App accounts. I clicked around every Google Mobile page in existence and couldn’t find a link to Google Calendar that let’s you sign-in to your Google Apps account. So as a last-ditch attempt, I tried taking the URL from my full-sized version of GCal and it worked!
For reference, if you want the mobile version of your Google Calendar for your Google App account, navigate on your iPhone to http://www.google.com/calendar/hosted/YOUR_DOMAIN.com/
You can’t edit your events, but it’s free so what do you expect 
And yes, by this post you can assume that I bought a 3G iPhone 
Just thought you would like to know that you can ADD to the calendar in this app. scroll to the bottom of the page and there is a box for “quick add.”
[...] recorded first by eguli on 2009-01-29→ Google Calendar for Google App accounts on iPhone [...]