I've just noticed these messages too though they appear at different times:
Apr 24 09:31:00 computername mDNSResponder: Permission denied (NOAUTH): _smb._tcp.i_have.members.mac.com.
Apr 24 09:31:00 computername mDNSResponder: hndlRecordUpdateReply: Registration of record _smb._tcp.*accountname*.members.mac.com. type 12 failed with error -65537
I think a security hole in 'Back to my Mac' was to blame (which, as far as I was aware, was turned off).
I think I had it enabled before I upgraded to iCloud, for some reason it was still trying to register for some old MobileMe web services and probably opening up ports in the process.
Turning both iCloud and MobileMe on and off a few times seemed to switch it off.