The new themes consist of ‘Ambiance-Maverick-Beta’ and a darker variant which can be applied via the Appearance properties window. Both sport neater, softer and more curvaceous looks.
The staple Ambiance and Radiance themes of Lucid remain included, too.
If you’re too impatient to wait for this update to filter through you’ll find the .deb available here but note that it depends on Murrine engine 0.90.3+git20100810.