I've been thinking for a while now about some kind of distributed image hosting, run on a volunteer-basis by interested forum members. I've also been thinking about a new BBCode tag to specifically reference content-addressable images that are being hosted in this way. If that project ever gets off the ground, then I can see a way to make uploading images feel like a completely built-in feature (but without getting theymos tangled in administrative/legal issues).
That sounds like a really nice feature, but I can think of so many ways it can fail. To start, what if one of the hosts replaces images by his own? This is one of the things I'd like to see, but the fact that nobody has done this before makes me think the drawbacks don't outweigh the benefits.