I have the iPad 64gb purchased in Australia, and when I was using it with my Apple Airport Extreme base station (2006 model) with no dual band or gigabit Ethernet support, it was running on WPA2 (AES) on the WiFi N (B/G compatible setting), and would randomly drop connection despite full signal strength.
The wireless signal icon on the ipad would flicker when it disconnected and reconnected. It only started doing this the last week, and the Apple Airport Extreme was running for 3 years 24/7 and never missed a beat, but in the last week the wireless drops affecting all devices got worse and nothing had physically changed. It was a sign it needed to be laid to rest.
So I bought the latest Apple Airport Extreme, used the same WPA2 (AES) encryption, have dual bands enabled which apparently cause problems, and no wireless device has dropped connection, I watch the iPad wireless icon like a hawk, and it has never dropped since replacing the router. This sees to indicate the issue may be hardware related.