I was noticing there was an "Images" menu choice when I was looking thru the web client. I searched the docs and didn't find any relevant results. My assumption was they would be for a screen saver to come up when shows are paused. (maybe not currently recording shows, but ones already on disk but I would think that could work too as its actually recording on the server not on the client)
We really love seeing our best pictures display after pausing a show. Especially when company is over like during the holidays. Always get comments when we are hanging in the living room and they are playing on the TV, usually someone sees one and asks if we can go back as they saw something they may have been in or something else of interest. [of course Sagetv doesn't have a way to go back 
] Is there a wishlist we can add to, and maybe vote on for inclusion? -Bill
Screensaver is controlled by the OS.
You can set up your photos on Google TV or Apple TV settings
Images in Channels are not related to personal photos.
Images in Channels are for uploading your own custom art to be used for TV, Video, and Movie posters, thumbnails, etc.
Channels is not, and has no plans to ever be, a manager for personal photos or music.
Bummer! I have tried a couple apps on my Shield and they are pitiful. Apparently I will need to keep my Sagetv on that so we can have Slideshows of our favorite pics... -Bill