What if you backed up, but no one else did?

This eWeek article got me thinking-how many of us do our disaster planning in a vacuum? I know I am often guilty of this, and it's hard not to be-you have a single company that you are working for, you are tasked with keeping their systems up and running, it's difficult to make yourself think outside that realm to consider other, intimately related issues. It's less excusable for me, if anything; I'm a consultant, I work with a lot of different companies, I should see these things coming. But if it's difficult for me, then it's probably even harder for the average CIO who has only his own business to focus on.
The article is about "Wall Street West," an aggregate disaster recovery hot-site in Pennsylvania available to various New York based financial institutions. You might be surprised to read about such an effort, thinking that every financial institution in the city went out and made significant investment in disaster recovery and business continuity systems immediately in the aftermath of 9/11. Well, they did. What they didn't do was come up with a way to tie it all together.
Any given financial institution or trading entity is relatively worthless without the connections to other such entities that allow them to do their business. So while each firm individually might have its own backup plan, that plan may have proven irrelevant if their significant trading partners did not, or if the plans were somehow incompatible; say you were setting up to recover out of your London office, while a significant business partner was going to work out of Tokyo. Not insurmountable, but certainly not a smooth recovery effort.
Do your backup plans, then, include considerations for those of your major business partners? Is your supplier in the warehouse next door, and if so, do you happen to know what he is going to do if an earthquake razes your block? It's been a matter of course for years to ensure that significant business partners have some stability to their IT operations, but I think it has been less common to consider the integration factors between various business continuity plans. If you haven't thought about it yet, then like Wall Street, you probably should-it would be a terrible fate to have your own disaster recovery plans function perfectly, but to then still go out of business because those of a partner do not.