I have been involved with a small company where there was little recognition of the "fabric effect" created by having multiple online presences. As webmaster it was my responsibility - I thought - to make sure there was some coordination, or at least some crosslinking going on (plus a mdoicum of SEO work done). Sadly there was little recognition of the need for this, and those duties were given to some else who has few if any web skills. As a result the organization will not get the full benefit of those sites they have labored to create, and they will be of use only for those people who are already part of the oprganization.
To me this is a waste - sites should not only be sources of information for those already involved (for a business, the customers, for a nonprofit, the members), but also serve as a resource for those who stumble across it....and you increase the "stumbling odds" by cross-coordinating the virtual fabric created by these multiple threads.
There are 2 organizing principals I have seen at work in the virtual companies. The first says that everything should spring from some central location - perhaps the primary company website. The theory here is that one central location makes it easier to find, and from there a potential customer can locate just about anything.
This version requires significant search engine awareness when designing the primary website - and even much MORE awareness when looking at the online fabric that makes up the virtual version. If there is only one entry point, then there MUST be some effort and time put into making the site search engine friendly, and some effort spent marketing the site in some form.
The other school of thought what I call the "Cast your bread" model - a biblical reference that is particularly appropos. The original quote reads "Cast your bread upon many waters......". In this case I am referring to the idea of having multiple online presences, each cross-linked and referring to each other. IF all of the resources are search engine friendly, then you increase the odds of an online browser stumbling across your resources.
So what's a webmaster to do when cast aside? In my case, go find some other clients!