Why don't you and future posters stick to the original question!
Okay: It's not secure at all.
Happy?
it's basically as secure as any file sharing that occurs on your WiFi network. If you've got WPA/WPA2 with a strong passphrase, or even 802.1x running on your Wifi network, then it, along with everything else, has a decent level of protection on it.
If on the other hand, you have WEP, or aren't running any sorry of encrypting at all, and your access point is wide open, then your Wifi sync is as insecure as your web browsing is. Let's hope you use Facebook, Google apps/mail/+, and anything else you want private over SSL, otherwise it's all out there in the open.
I have asked a question because I am interested in factual information with regards to the security of iTunes WiFi syncing. Nothing more and nothing less.
Fact: like most wireless traffic over your network, wireless syncing is probably depending on the transport layer to be secure. If you don't have your Wifi secure, then WiFi iTunes syncing should be the least of your concerns.
So, if you're
really that worried about whether your neighbor is snooping on your WiFi and will find out that you still listen to
Hanson, then you should stick to cable syncing. WHile you're at it, you should probably take down the router and go all-ethernet cable, before that pesky neighbor discovers more damaging info than that.