Setting the body will save the announcement to the db.
Did I miss some documentation about this?
I'm assuming that changing the other attributes (startDate etc) will also cause a save back?
I also can't see how to set the properties?
Okay, I'll answer my own question about the properties.
It appears that you get the property Map with getProperties and then you can add your own properties and I guess this will trigger a 'save'. Although, I can't fathom out when the save takes place, is it every-time I add or update a property?