The XPlanaZine article by Susan Smith Nash appears to have kindled some thoughtful commentary on the blogosphere (on a Saturday, no less). I agree completely with her reservations (as well as those of Darren Cannell). Reusability is pretty much a fallacy, especially when attempted with highly complex "learning objects" like websites, powerpoints, etc...
Real reusability becomes more difficult (and less useful) as a resource becomes tailored for any specific context (by adding complexity via structure and content). This is David Wiley's "reusability paradox", and there's no easy way to get around it.
Real reusability is only effectively possible when dealing with smaller resources. Images. Video clips. Audio clips. These smaller bits can then be more readily recombined with additional contextual information (structure, content) to provide another use of the assets.
Once a complex resource becomes meaningful enough to be use used in any particular context, it's usefulness in other contexts is reduced or eliminated. But, if you can go back to the source, to the image/video/audio assets that make up the complex resource, then you can build a new "learning object" that is tailored to your particular needs. Which will almost automatically be unusable in any other context. But that's OK, if other people can go back to your source assets and create their own complex resources...
That's pretty much the idea behind Pachyderm, and it's why I'm so excited by what the software can do. Reusability does not live in the final output product - the interactive, highly contextualized resource. It lives in the raw assets that were used to create that resource. By using the Rip, Mix, Burn philosophy, you can recombine assets as needed to fit your own particular needs, at a particular time, for a particular audience.