The American Academy of Pediatrics continues to recommend that children above age 2 be exposed to no more than one or two hours of screen time per day. They recommend that children age 2 and under have no screen time at all.
Have a read on this article http://preschoolmatters.org/2011/06/30/child%E2%80%99s-play-should-...
The Alice app for Apples's iPad Tablet has a pop-up book for young readers to manipulate images as they read to encourage interactive readers.
I think incorporating technology into a preschool classroom is important. Check out my page, I am continuing to add articles about technology such as Skype, digital cameras, and video recordings fun and educational for young children. You can even use Skype to have a teacher parent conference, or if the parents want to Skype in during the day and see what your classroom is up to. Also, digital cameras are great for younger children they can create their own art, and build their own books and tell a story (digital storytelling)...this builds imagination and vocabulary.