Today, iOS 5 beta 4 has been released to developers.
Mostly it includes bug corrections, huge stability corrections and the long awaited: iTunes Wi-Fi Sync for Windows.
However no iTunes 10.5 beta 4 for Windows has been seed as this writing.
For first time in the betas, you can simply update "over the air" (wifi required), without the need to install itunes at all for the update.
Long time still is in front of us before final iOS 5 arrives us in Fall, and with every beta more things are polished to perfection.