The ReturnCode property of the NUnitTeamCity task seems like an obvious candidate for something that should be accessible when the task exits. However, if I define a task like this:
<Output TaskParameter="ReturnCode" ItemName="NUnitExitCodes"/>
I receive the following message:
error MSB4065: The "ReturnCode" parameter is not marked for output by the "NUnitTeamCity" task.
I think this should be a simple matter of adding an attribute - is this something you could fix in the next release?