Redundancy
I work for Urban Wimax who provide symmetrical business connections of up to 10mb over Microwave, completely separated from BT's infrastructure. Whilst I do feel sorry for businesses who have lost money due to this outage it really is time that resilient data connections are taken seriously, and not just seen as an extra cost to businesses. I think this proves the case very well that as soon as your phone line or internet connection leaves your building you really don't know where it goes or who has access to it.