We have a quite a few old posts with hotlinked images (they predate the SE imgur account). The problem with these posts is that the image at the original URI is beyond our control, and can be taken down at any time. What that leaves you with is an ugly non sequitur of an alt text in an otherwise nice question/answer.
Is it a good idea to automatically start pulling inline images in posts predating August 2010 (the ones that are still online, anyway) into the imgur account? That way we don't have to worry about potentially decent posts turning into this.
Note: IANAL, so I haven't really considered the legal ramifications of this. If you foresee legal issues, please feel free to point them out.