We had the following question come from the Photoshop.com blog that covers the Gallery changes:
Question: "When I try to create a express slideshow it will let me pick out a template then I can’t add music or get a timeline or anything else for that matter !! Have talked with your tech. help people & that got me no where ..."
Answer: Our slideshow engine did change recently, and the ability to add music, as well as the default slideshow experience, changed. In the case of music, it is not available at the moment (but we realize that it's a really nice feature to have. For the time being, you can create excellent slideshows with music and transitions and effects, using either Photoshop Elements or Premiere Elements, and share those on ps.com).
The default sharing slideshow also changed, from that 3-D floating model to the new Midnight theme. The primary driver for that change was to drastically improve the loading time for the slideshows, and in fact, the slideshows now load in a fraction of the time, and offer a superior viewing experience with real full screen, as opposed to the previously limited large view available in the former model. But we're adding new themes and templates all the time, and we understand the appeal of a deep, interactive experience for sharing slideshows. Again, in the meantime, until new themes come available directly online, you can choose from a variety of very interactive and fun themes if you share photos and video directly from Photoshop Elements or Premiere Elements to Photoshop.com.