Wi-Fi certificate of IPad 3 is exactly the same as for iPad 2
iPad 802.11n draft 2 2.4 GHz (antenna 1:1) Certificate
iPad 2 802.11n 2.4 GHz, 5 GHz (antenna 1:1/1:1) Certificate
iPad 3 802.11n 2.4 GHz, 5 GHz (antenna 1:1/1:1) Certificate
Some other devices:
Mac mini 2011 802.11n 2.4 GHz, 5 GHz (antenna 3:3/3:3) Certificate
Mac Book Air 2011 13″ 802.11n 2.4 GHz, 5 GHz (antenna 2:2/2:2) Certificate
Lenovo X201s (Intel WiFi Link 1000 BGN) 802.11n 2.4 GHz (antenna 2:1) Certificate
iPhone 4S 802.11n 2.4 GHz (antenna 1:1) Certificate
other devices http://certifications.wi-fi.org/search_products.php
iPhone 4S 2.4GHz 802.11n
iPad 2 5GHz 802.11n
iPad 3 5GHz 802.11n
Lenovo X201s 2.4GHz 802.11n