Can I use a New iMac 21 inch with my 2010 model for display?

[kompletemail]

I would like to purchase a new iMac and use it as a second monitor I hear that the new iMac models will support video display in and was wondering if I could use my older 2010 model as the main computer and a newer iMac 21 inch as the second display?

 

[old-wiz]

iirc only the 27" iMac functions as external display and then only from a thunderbolt equipped other mac.