I am surprised you guys are saying this to apply a screen protector on the iPad-2 when the screen of iPad is scratch resistant is what I have heard of. Yes harder materials like metal or sand molecule will leave a scratch on it but, in normal use it is unlikely that it will have a scratch on it with normal use. And I hate putting screen guard on my device especially when it boasts a scratch resistant screen !
All glass is not the same. This is the toughest glass available. Diamond hard material can scratch. But it generally takes a lot of abuse to cause problems.
The following is a copy and paste from Anandtech in depth review of the iPAD2.
"The iPad 2 and previous iPad both utilize Corning Gorilla Glass. This type of glass is an alkali-aluminosilicate, being primarily silica and aluminum with an alkali metal, along with other unspecified components mixed in to tweak its properties. The biggest benefit of alluminosilicate glasses, aside from being relatively tough to start with, is the fact that the rate of ion exchange is fairly high even at temperatures low enough that the structure cannot react, meaning it can be processed quickly and create deep protective layers in the glass. The iPad 2 has a modest reduction in the thickness of the glass (about 23% thinner, for those interested) compared to the first iPad, and the question of increased fracture risk has been posed. Given the identical surface quality between the two generations, the reduction of thickness should create no palpable change in toughness for the typical user. That is to say, a drop that would shatter the screen on the original iPad would likely do the same for the new model. That being said, several other design changes appear to account for the change, and might yield better performance in this department.
Where its predecessor used small metal clips to retain the glass screen, the current iteration uses a ring of adhesive around the entire perimeter that not only distributes the load around the glass and prevents scoring at the glass-metal interface, but better couples the stresses into the more compliant aluminum frame. Both of these measures should improve the performance; either way, drop-testing new electronics is generally not recommended. "