http://news.cnet.com/8301-13579_3-57538470-37/to-apple-thanks-for-making-my-new- ipad-obsolete/
Hi, Please see the above cnet.com article. Call your local Apple store if you bought one there or check with sales support if bought it on Apple's on-line store. They very well might exchange it for the ipad 4 if you bought it within the past thirty days. The decision by Apple stores to do this is discretionary.
I'm not sure if it's in the US only, or if other countries are participating.I hope this helps.
Please note this is not the only article. Many have posted others and on some threads a few people said they spoke with Apple and it is true. (You'd have to search pretty far back on today's threads only, but they are there.
It has also been on the news.
Give it try. Particularly with electronics, I never find a store that has more than a 14 day return policy (which I hate!) So if Apple's willing, great for you! Act fast, though.
Hope this helps.