This has been the ultimate project for me, and is now finally functional after 8 months of blood, sweat and ABS.
It is also made on my 3d printed makerbot ( thingiverse.com/thing:3285 )

The printer can easily get taller by adding more z-elements and replacing z lead-screws and wobble arrester bars. I would then end up with almost 800mm build hight.

It wouldn't surprise me if this is the largest printed multi-piece object, as it is built from 15+ lbs of ABS plastic.

Specs
Footprint: 800x560
Build envelope: 500x300x200+
Platform: Heated with 800W, custom ordered, silicone wire wound element.
- Kapton sheet, custom ordered to fit platform (500x300)
Motors: NEMA 23
Extruder: MakerBot Stepstruder® MK6 Plus
Electronics: MakerBot® Generation 4
Interface: PC/Mac or MakerBot® Gen 4 Interface Board Kit v1.1
Motion: all axis uses linear bearings for smooth motion.

Build duration: 8 months
Plastic used: 15+ lbs
Price: 3000$ (approx.)

Video of the printer in action: youtube.com/watch?v=Cx2OUO-aSFQ