Apple has not mentioned whether or not the iPad will support LEAP or PEAP Wi-Fi authentication. iPhones already have EAP (Extensible Authentication Protocol) support via the iPhone Configuration Utility. Since the iPad will run iPhone OS 3.2, it's likely that support for these will be included.
iPhone users are limited to WEP, WPA, WPA2, WPA Enterprise, and WPA2 Enterprise when connecting to Wi-Fi networks without custom configuration profiles.
The iPhone Configuration Utility supports TLS, LEAP, TTLS, PEAP, and EAP-FAST.