As the iPad 2 is much more powerful, having a way to easily distinguish the two would be really helpful to be able to add eye-candy; and it would be unfortunate if we'd had to wait for Unity 3.4.
My recommendation would be to write an Objective-C plug-in (PRO-ONLY) if you can similar to what is described on this thread.
For now I would check for iPhoneGeneration.Unknown as this should be most likely iPad 2 in Unity 3.3. Check this post http://forum.unity3d.com/threads/81257-iPhoneGeneration.iPad2Gen-...?highlight=unknown
Maybe the graphics information from SystemInfo could do the job?
According to the release notes for Unity 3.4 “iPhoneSettings.generation now recognises iPad2”.