Upon waking, my iPad would often prompt me to re-enter my WiFi password, or simply say that it wasn't connected to the internet. I was using an old D-Link Router with 64-bit WEP encryption. After talking to a senior support tech, I switched the WEP to 128-bit and it's been smooth sailing ever since. (He said he recommends 40-bit or 128-bit, just not 64-bit. Mine doesn't have 40-bit.) This is still a bug, because if you're in some random hotel, you can't change the router settings. But this workaround may help until a patch is released.