I just got an iPad 2 yesterday (my very first iPad) and upgraded it to iOS 5. I connected it to my MacBook Pro to sync and checked the wi-fi sync box but when I unplug the cable the iPad disappears from my iTunes sources. When I go into the iPad settings I do have the option for wi-fi sync but when I click the "sync now" button it just says "Looking for MacBook Pro" and never finds it. Now, I also have an iPhone 4 and it is able to sync just fine over wi-fi to the same computer on the same wireless network. Also, the iPhone 4 automatically shows up under iTunes sources when I'm connected to my network. I'm running the latest versions of everything (Lion, iTunes 10.5, etc..) It's just weird that one device works fine and the other doesn't. I did try quitting and re-launching iTunes and that did not help.