Yes, the Panny definitely includes Oly's "Supersonic Wave" dust reduction system, a system I can attest works very well indeed in the Oly E-cameras.
The 12 MP sensor is new, and I suspect will be rolled out into the next generation 4/3 dslr bodies, which are currently 10 MP.
I don't think Panasonic are capitalizing on the µ4/3 small size potential at all with this effort--either in the body or the lenses. I await Oly's first stab with much anticipation, hoping they keep the body small and by incorporating in-body IS (which they surely will), keeping the lenses small as well.
I sometimes shoot with an EVF camera w/0.5 meg resolution, and it's not bad considering how much lighter and smaller it makes the camera compared to an slr. 1.5 megs, especially if it's also bright and contrasty, might just be a breakthrough for the technology (although I suspect OLED will dominate displays eventually).
Panny's target market for the G1 sure ain't woodsy outdoor types, based on their own Web page.