I think you are correct about the Samsung SSD's in the UMBP's. X25-M from Intel performs very well and the OCZ Vertex seems to be getting great reviews as well. Now if they just drop in price a bit
Apple uses the Samsung MLC SSD for the 128 gig CTO. This is the "previous generation" drive as Samsung is moving to a new controller in their newer 256 gig model, which should then trickle down to the other models as well.
Buying it from Apple will be more expensive than doing it yourself. You can buy the same drive from Corsair. Look for the Corsair 128 gig SSD. It's the same one Apple uses and you will save yourself a few hundred dollars.