On my Windows 7 workstation at work, I use FlashBuilder 4.6 to debug iPad apps all the time. The process is simple and reliable -- start the debugger which begins waiting for the app to notify it, move the app into iTunes, move it onto the iPad, launch the app, the app notifies the debugger that it is running, debugging works!
At home I am running Windows 7 under the latest version of Parallels on my iMac running the latest version of Lion. I go through the same process: I connect my iPad (the same one from work) to the Windows VM, and Windows iTunes recognizes it and syncs files just fine. I can move a non-debugger version of the app onto the iPad and it runs just fine. However, when I start the debugger in FlashBuilder and then move the app onto the iPad and launch it, the app is not able to find the Flash Debugger. When it launches I just get a black screen for about 2 minutes, then I get a message asking me to enter the IP address of the Flash Debugger.
There is an old help document indicating that this is due to the iPad and then debugger host computer not running on the same wifi, but I don't think it's relevant. My workstation at work isn't even connected to wifi.
I will consider any advice. It's pretty important for me to get this up and running at home. I tried running directly under bootcamp, but both Microsoft and Adobe consider the bootcamp install to be a unique install of their products.
It turns out that the "help document indicating that this is due to the iPad and the debugger host computer not running on the same wifi" was spot on. At my work environment, the wifi and the ethernet lan are on the same network. I was mistakenly assuming that the iPad and the debugger were communicating via the USB cable, but this is not the case. I think what happens is that FB embeds the ip address of its computer in the debuggable app. The app then connects to FB at that IP address.
My problem was that I had the Network Settings of my VM set to "Shared" under the Parallels hardware config set up. My VM then had a 10.211.55.x ip address instead of a 196.196.0.x ip address, which is the range of addresses on my LAN. Changing the setting to "Shared" fixed the problem.