Chip Design Magazine published an article by me in their August/September 2008, about Getting Software into the Hardware Design Loop. The article is about the technical and marketing aspects of how chip designers can get early feedback from software and systems designers, early in the hardware design process. The vehicle for this? Virtual platforms, obviously.
A key idea here is to start with a fast virtual platform (which means Simics-style, obviously, considering my background). Such a fast and low-detail virtual platform can be built very quickly and will run very quickly, which makes it possible to get it out to customers early and get feedback on functionality, programming interfaces, etc. And to get partners to port fundamental enabling software such as operating systems and network stacks to the target. The key here is really the speed of the simulator, as it directly impacts the productivity of the partners.
Once the target software is up to some extent on some version of the simulation, you can start to collect feedback. Later, at some point, more detailed models with lots of timing information will become available, and using the now working software, you can evaluate the detailed performance.
A current example of this kind of two-wave approach to virtual platforms is the QorIQ P4080 Hybrid Simulator. While the cycle-accurate models are being developed, the fast models were used to get software in place.