Google released the new Photos app at Google I/O a few weeks back, and this is the first significant version number change it has experienced since then. There doesn't seem to be much on the surface to justify the jump to v1.1. You can still grab the APK and install it now, though.
So far, all we're seeing is a change to the overflow menu in the main photos screen and a different icon for videos in search. The view options in the photo stream now list comfortable, month, and year views. Before it was comfortable, compact, and month. You can still use multitouch to change the zoom level as you like. In the search interface, the videos link at the bottom now has a circular icon instead of a square one.
The update is available on APK Mirror for your sideloading pleasure. We'll keep poking around to see if there's anything else of note.
- APK Mirror