I have a thread going in the iPad 3 section but I'll post a brief summary here. I have the new 32GB Verizon model (no VZW service for it yet). It runs fine on my wifi and then suddenly loses connection, even with full wifi signal shown. Just says "unable to join network name". The signal meter does vary tho. In the same room as the iPad, I have a PS3, two android phones and two Win7 laptops all running fine without any wifi issues and no variance of signal strength. The wifi router is actually less than 20' away in the next room.
I updated firmware on router as it was outdated, but that did not help. When it drops connection, it may take 10-15 minutes before it will be able to reconnect. Other times it may take 1-3 minutes. In most cases, the network is shown as available and with mid-to-full strength, just unable to join. Sometimes it does not show the network as even there, but not as often.