Is is possible to create a fixed text field that will default to some pre-defined text upon card creation, but then be read-only? I suspect this is coming in the next version but need to know if there's a way to implement it now.
Yes you are right.
At this moment it is not possible to define default values for an attribute of a card.
This and other similar activities are currently planned in the second half of 2015.
They were delayed compared to the previous roadmap, because we’re still working at the “mobile” interface and at the new GUI Framework, and after we will start with the rebuilding of the Relation Graph.
CMDBuild Team