Yes, Rust Console Edition is cross-platform between PlayStation 4 and Xbox One systems. By default, the game will show you a variety of different servers, which will include cross-platform.
You may also only wish to see servers which are only open to the platform you are playing on. These servers can be found by doing the following:
- Go to the Find a Game section
- Select either PlayStation 4 only servers or Xbox only server
The platform of your choice will determine what is available to you. For example, if you are playing on a PlayStation 4, you will only see the PlayStation option.