IMAX created GT (Grand Theater) and SR (cost reduced) products still targetted mostly to museums.
The MPX product is very different and sized to fit in multiplex theaters. 3D capability is pre-built into a single relatively compact projector.
IMAX was an early participant in Digital Projection although originally targetted as a business expansion rather than a replacement or competition for the mainline IMAX product. DPI was bought and then sold in 1999-2001 but did create and release a "DigIMAX" projector line.
The most recent plans as of early 2007 are to use 2 Sony SXRD 4K projectors with some IMAX customizations. This would not provide "IMAX" level 15/70 picture quality but should be far better than other Digital alternatives and if successful could lead to true IMAX level digital projection.