OmniFocus for iPhone and iPod touch - cool. Combining the iPhone OS's Location Services with a GTD application. Obvious idea, but you still have to come up with it first. Additionally, there will be a sync between Mac and iPhone for OmniFocus - that makes the software quite interesting - especially of course if it is based on elements and possibly even can synchronize several OmniFocus instances? The latter probably not, but one can still hope.