I just wanted to post a few observations of mine about the iTunes/sharing issue.
1st off, I've got a DNS-321, ver A2 with 1.03 firmware.
I have 3 machines I'm currently running iTunes on. 2 are WinXP 32 bit (a desktop running WinXP pro and a laptop running WinXP MCE...yeah, I know, it's really pro too) and a laptop running Win7 64bit Premium. The two laptops both have iTunes ver 10.0.1.22, and the desktop is running 9.2.1.4.
Reading the posts here and elsewhere I fully expected the two machines running 10.0.1.22 to not be able to read my iTunes share on my brandy spankin new, just configured DNS-321. To my surprise, the XP laptop running iTunes 10.0.1.22 reads and streams the NAS share just fine, as does my XP desktop running iTunes 9.2.1.4. The Win7 laptop, however, can't seem to see either the share on my DNS-321 OR on either of my two XP machines. Oddly enough, I can view the iTunes share on my Win7 laptop from either or my XP machines.
I've reinstalled iTunes 10.0.1.22 on my Win7 64bit laptop, and get the same result; I can't see any shares, but my 2 other machines can see the shares on it. Seems like an Apple/iTunes problem to me.