Pretty rare and overblown. The issues only affected some campus wifi networks with short DHCP leases. iPad has some unique features that allow it to receive push emails and notifications even while it is in sleep mode, by keeping the wifi connection active. Apparently it isn't yet smart enough to renew it's DHCP lease while in this sleep mode, so it was staying on a leased IP after the expiration time.
You were probably only affected if you were using an iPad on specific University campuses, and I see no reason why the network admins couldn't work around it by giving out longer DHCP leases to iPad specific hardware, at least, until an official fix was issued.
The iPad has overall been surprisingly bug free for a 1.0 product.