Turn your iPad into a DSLR with the Padcaster.
I picked this up from ICG magazine of all places. The Padcaster is a housing for the iPad that will let you add tons of accessories. The Lenscaster let’s you add lenses. I could not find out too much info on the lens mount but it looks like manual focus and iris only. The Padcaster sells for $149 and the Lenscaster Padcaster combo is $189. Here is a rip from their website.
“The strong yet lightweight aluminum frame comes equipped with both 1/4-20 and 3/8-16 threaded holes lining all edges of the Padcaster. Attach external microphones, lights and other camera accessories to enhance filming with the iPad. A tripod thread and locking-pin hole let you easily connect the Padcaster to a tripod, monopod or shoulder mount for stable shooting and a solid feel.
The Lenscaster is your Padcaster and iPad’s best friend. An optional accessory, it lets you attach your favorite lenses to the Padcaster, giving you control over the focus and depth of field for that film-like quality never before possible on an iPad.”