Just wanted to post this in case anyone else is interested. We have a datasync server set up for our iPhone and iPads but are using ldap authentication. I wanted to use some old iPads outside of our meeting rooms to display the calendars for those rooms, and after looking at all the somewhat expensive monthly cost services out there I decided I just wanted to use the iPad calendar with an Exchange setup to do this. The problem is that some of our room calendars are not ldap users, but are resources - so they don't have a password. After trying many different things, I finally decided to set up another gwsync server using groupwise authentication instead of ldap - I added just the resources to that server and added groupwise passwords to them and now those calendars also sync on the iPads.
This was a very inexpensive solution for us to have the room calendars outside of the rooms - they are always up to date now and users can easily put themselves on the calendars right at the device if they want. We have 5 rooms and they are all busy all the time - so this is working out great for us.