What are you looking for those products to do with respect to Fences?
Well, you can use Fences to define several desktops with different sets of desktop symbols, right? Switching between them is done by dragging the right and left desktop borders.
DeskScapes should be aware of this action and switch its backgrounds along with that. I think it should easily work with static backgrounds, and the user could define transition effects, like it's done in picture slideshows. Or define a dual-monitor-wallpaper (like <these>) and use a parallax effect, like it's used on some Android homescreen apps. - I fear that animated video backgrounds would consume too much resources.
I only read about what Tiles (Beta) can do, namely defining multiple desktops with different sets of desktop icons and arranged program windows. It's more than obvious which type of communication should be implemented here: each desktop should be able to to have its own set of pre-defined fences.