It seems that there have been a number of people complaining about the wifi connectivity on the iPad. Having good wifi is pretty important and so far Apple are not really addressing the issue. It has taken Princeton University is jumping in with a possible explanation for the problem. Now they reckon that the problem is caused by the operating system rather than it being hardware related.
The network guys at Princeton found that the connection issue comes up when the iPad fails to renew its DHCP lease – a process which would renew its IP address with the router is is connecting to and then continues to try as use the same IP. The router might block what it thinks is a lapsed IP, or it may have assigned that address to another wireless client. The sometimes the iPad does’t refresh its DHCP even when a full connection isn’t being made, leaving the user unable to get online.
Workarounds include performing a full power cycle (i.e. not just locking the iPad but fully shutting it down and rebooting it) and turning the wireless off and then on again in the iPad’s settings. Moving outside the WiFi router’s range and then back into it again has also been shown to help on some occasions. Too me it all seems to be a bit hit and miss and we will have to hope that Apple will come up with a good solution to the problem soon..