This is my set up, and I hope it helps everyone to clarify the way photostream works:
iPhone (mine)
White Macbook (wife)
Mac Mini Server (mine... well "home" server)
iMac (Kids)
MacBook Pro (mine)
Photostream is activated on iPhone
Photostream is activated on AppleTV 2G
Photostream is activated on Wife's MacBook, Kid's iMac and "my" MacMini "Home" Server (but only "Automatic Import)
Photostream is activated on MacBook Pro (both "Automatic Import / Automatic Upload)
Take a photo with iPhone.... it goes into Photostream (iCloud), then it downloads and IMPORTS automatically on all Macbook, iMac, MacMini Server, MacBook Pro.
I also have a Nikon D3100. The pics I download from the Nikon, go into my MacBook Pro. Because on my Macbook Pro I activated Automatic Import and Automatic Upload, those pics from my Nikon, go into Photostream, and are imported automatically into the iMac and the MacMini.
Now, when photostream reaches "1000" pics, those pics are "auto-importing" into all the iPhotos's. It automatically creates a "NAMEMONTH 2011 Photostream" event that avoids having to import the pictures with a cable from the iPhone.
It's been working great so far, so I have not had any problems.
Now on my Photostreams on the Apple TV 2g and iPhone are always the latest 1000 pictures (or latest 30 days) at all times all across my family, without having to send them across... all via wifi.
You might be wondering why I have such a set up:
Mac Mini "Home" Server has now an exact copy of the library from the MacBook Pro. Well I also have an Apple TV First Gen, which gets all the movies and photos off the server.
The Apple TV 2G, also allows me to get all my pics and movies off that server.
My wife's Macbook only contains the iCloud photostream, so each month, an "event" is automatically generated on her macbook iphoto's library.