VERY interesting that they are using an unmodified stock LCD! After struggling a long time with a UV setup, this seems almost impossible to me.
http://www.panelook.com is an awesome resource for LCD info. Using the advanced search you can search by brightness.
Looks like the iPad has a brightness of 400. If that was giving you trouble, I'd assume we'd need something with a higher brightness.
Searching by 1024x600 and sorting by brightness reveal the highest brightness panel to be 1000. I assume they are using one of these panels.
I bet curing would be crazy fast with an LED array though. We'd probably wouldn't need to worry as much about unevenness of light because you could place the light farther away or use a diffuser.