Not sure "answered" is correct for this post, it seems pretty likely it's a bug, even if there is a temporary way to get rid of it via sliding to the search screen.
For me it was showing up in the home screen, any app when you bring up the task switching bar, and in fullscreen apps (which is most annoying). Not intended to be an exhaustive list, just where I saw it.
And it still stays in the same physical screen location when in landscape mode, by the way (see screenshot of fullscreen landscape video in iTunes app).
http://staff.osuosl.org/~emsearcy/iPhone4bluetriangle.png