OK, yeah:
The Intac is a "corneal ring"; the doctor makes an incision near the cornea and the ring is inserted (under the epithelial layer?). The ring distorts the cornea a certain amount to change the focus point to line up with your retina. These are supposedly removeable.
The implants used for cataract surgery are a complete lens replacement. They are starting to be able to provide multifocal lens replacements that eliminate the need to use reading glasses. The way I understand it, the implants are custom-ground (molded? formed?) to correct your vision to 20/20.
Intacs:
http://www.swmed.edu/ophth/krings.htm
Multifocal replacement lens:
http://www.richmondeye.com/array.htm