Heather Nova's official site has a message from her about her recent collaboration with ATB. She has co-written three songs with ATB: Renegade, Stars Come Out, and Made of Glass. All three will appear on ATB's upcoming album, Trilogy, available for pre-order on amazon.de.

Trilogy (1-CD edition)
Trilogy (2-CD limited edition)

EDIT: Heather Nova has not only co-written these three songs, she also does sing on them!