I have 16 AppleTVs connected to a Video Wall, we want to share the iTunes/iPhoto libraries from a Mac mini containing family photos so we can show different photo albums in each screen (up to 16, one for each AppleTV in the video wall). Does anybody know how many simultaneous connections iTunes can support? We will showing personal media, no movies or music bought from the iTunes Store.
I don't see any reason why there would be a programmed limit since OS X server can serve hundreds of computers from the same share and to intentionally break the n'th connection would be poor form to program if there weren't a way to set that limit.
Photo sharing is very low bandwidth compared to HD video streaming, so you should not have any problem with 16 large images - even if they change once a second since a video stream is basically 24 fps and I've had more than three Apple TV stream from the same library on a MacBook Air without running into network bandwidth or IO contention issues.