"This emulator is fundamentally different to every other emulator I know of, in several critical ways. I'll publish more about that towards the time of release, but most importantly, Exodus is not a Mega Drive emulator. Exodus is a generic emulation platform, which allows systems to be assembled from individual components at runtime. Nothing related to a particular system is hardcoded. Exodus constructs a system from a set of discrete components, manages the communication between those components, and keeps perfect timing accuracy between each component. Other systems can easily be modelled without modifying or rebuilding Exodus, it simply requires emulation cores for each device in that system to be available."
MAME has been doing basically this for 15 years-- arcade cabinets are simulated by combining various common chips (CPUs, video drivers, sound chipsets, ROMs...) with a small amount of glue code.
Moving the glue code from a .c file to runtime makes it faster to tweak, but it's not a new idea.
The gem5 simulator (http://www.gem5.org/Main_Page) sounds like it works in a similar way to let you hook together different components and simulate different systems. Although gem5 is a research tool and not targeted to specifically emulate real devices.
Woah...this could be extremely cool.