I keep all my photos on a storage server, organised in folders by year, month, date of capture. So my file structure looks something like this:
- 2009 - 2010 - 2011 - 2011.01 - 2011.02 - 2011.03 - 2011.03.01 - 2011.03.02
This is for storage of originals only. You would need to import photos from your phone and camera with something other than iPhoto (for example OS X built-in Image Capture app), then copy the files over to your storage server. This could be automated, but i do it manually, reviewing the photos and removing duds.
I then use iPhoto to grab the photos from the storage server, so they're stored in the iPhoto library of my main machine.
Some or all of the iPhoto library can be shared in Preferences > Sharing, so that other iPhoto machines on the network can see the contents of the library.
This should work for you as well, i guess. It's not really elegant -- what i'm looking for server version of iPhoto -- not sure that day will ever come!