OK, here's what I did:
This works on 2 (and probably more) Macs
without messing around with any port settings
with OS X Preferences, Sharing, File Sharing turned OFF on BOTH computers
with iTunes Preferences, Sharing, "Share my library on my local network" turned OFF on BOTH computers
(apologies for documentation overkilljust being thorough)
1. Turn OFF Home Sharing on BOTH computers (this is NOT done in Preferences; instead, go here: Advanced, Home Sharing)
2. Make sure BOTH machines are authorized for BOTH iTunes accounts (Store, Authorize Computer)i.e., if each has its own iTunes account
3. You do NOT have to be logged into the same account on both computers; each computer may stay logged into the iTunes store under its own login
4. For sanity's sake on this part, check to make sure of thisi.e., that each machine is logged into the store with its own store account (Store, View My Account, check to see ID is correct)
5. NOW turn Home Sharing back on (Advanced, Home Sharing) on each computer, but use ONE account to log into Home Sharing on both (or all) computers
6. DON'T WORRY, this does not "flip" the login ID for a particular computer's iTunes Store connection to the ID being used for Home Sharing
7. On each computer now you should see a "Home" icon with the shared library in the left-hand sidebar
8. Open the shared library and drag and drop as desired
The bottom line seems to be this:
1. Keep each computer logged into the store with a separate iTunes ID (if you need to)
2. Get all the computers authorized for all available IDs
3. Use ONE ID to log into Home Sharing on ALL computers
You will of course ONLY see the Home Sharing icon pop up if both computers are on, with iTunes open on each
You'll know that this whole thing is working if the shared library listed on the left has the correct "Home" icon (and not the blue, "shared" icon that shows up when Preferences, Sharing, "Share my library on my local network" is turned onyes, this is the one you see in Internet cafes filled with Mac users)
I've tested the above over and over again, even completely rebooting my two machines (they have different iTunes accounts), and it still works. This is running Leopard on both machines.