Yes, you can share the tracks of one iTunes instance over the network to another. But this isn't what Mat was asking about. At least that's not what I picked up on since he asked specifically about moving the library to a NAS device.

When you allow sharing from iTunes, the instance where you enable sharing must be running for other instances to see it. That means, in Matt's case, the NAS must be on as well as his wife's computer, in addition to whatever other computer he's going to also use to play tracks. And playing is all you can do.

Lastly, the iTunes instances browsing the share can only see a flat list of loose songs. The tracks cannot be displayed with album artwork or grouped into any of the advanced views normally possible when browsing a "local" library.

I suppose in this fashion it sort of is a client/server solution, except that the clients are severely crippled when compared to the "server" iTunes instance. You also can't copy any of the music nor can you put it onto an iPod connected to the "client" instances.

My suggestion and instructions simply point various instances of iTunes to a library existing on a shared drive, but which iTunes otherwise sees as "local."