Ok, probably of limited interest to 90-95% of readers, but:
My iTunes artwork isn't displaying when I use aMSN. This obviously upsets me, hugely.
Lion is a 64bit OS, aMSN (both SVN and standard release) appears to be 32bit. And that's why the two don't play nicely.
But there's a quick fix.
Close iTunes. Go to the Applications folder, do a Get Info, and select Open in 32-bit mode.
This seems to work. Although I've noticed that you need to start aMSN before iTunes - especially if you use a remote storage location (NAS) for your iTunes library.
Why, of course my life is exciting.