It's actually not the first version of the iPad to see wi-fi issues. Back in 2011, reports came in regarding similar issues with the iPad 2 and iOS 4.3.
In fact, the workarounds given for the issues are the same as back then. You can tell iOS to "forget" the network, then re-add it. Or you can go into Setting and "Reset Network Settings, then reboot.
The investigation has not been made public, but rather came to light due to a leaked internal AppleCare document.
The issues have received a decent amount of coverage, as they usually do, at Apple's support forums.