I might be moving to Australia from the US and want to know if my iPad 3G w/w-fi would work there? I know my iPhone won't work there so I assume this won't either.
Should work fine, but you'll have to hold it upside down...
Your iphone wouldn't have worked with a local SIM because it's carrier-locked to AT&T. The ipad (1 & 2) is NOT carrier locked and thus should work work just fine with a local SIM. Just make sure, if its an ipad2 3G, that you have the GSM version not the Verizon (no SIM).