If it was that trivial, I would at least expect Google or Nokias Maemo to have come up with such an interface before 2007.

I don't think the work put in by FingerWorks, and then the work put in by Apple to create the iOS user interface was trivial at all. It may not have been groundbreaking compared to what came before (ie most had been demonstrated by researchers), but I think it's obvious that a lot of work and design decisions went into creating it.

Of course at lot of work and design decisions went into creating it (just as any UI), but it was a logical next step.