You've long been able to label FDO features with multiple line labels using '\n' in a concat string, as here: CONCAT ( ‘text’, ‘\n’, ‘this’ )
However, with the introduction of Enhanced Styles in 2012, that command changed for enhanced styles to '\P'.
I tried out this expression: concat ( TOWN , '\P', POPCH90_00 )
And got this result (the layer is also themed by POPCH90_00):
You can find more about this and other new features in 2012 here: http://docs.autodesk.com/MAP/2012/ENU/readme-map.html .
EDIT: You can use MAPSTYLE to change your default between Enhanced and Standard styles.
EDIT 2: MAPSTYLE doesn't really seem to make the difference. Rather, it's whether you are labeling with Plain Text (use \n) or MTEXT (use \P).