"There are some LCD controller exist with built in driver stages, multiplexers, pixel memory and so on. But I think, none of these with an 8051 core."

I think that this is what the Triscend offering gives you? (see banner ad)

I must also admit to never having used graphic LCDs, so I haven't done an in-depth evaluation. But it does sound like the kind of thing you're talking of?
Maybe Steve Knapp could expand on this...?

All the docs etc can be downloaded from the link I gave earlier.