This little Webkit gem is really nice to see: Bug 200764 – Main implementation for lazy image loading.
Chrome recently started supporting native lazy-loading, being the first, and so far only browser to do so. This concept is such a good idea, it would be a shame for it to remain Chrome only. Having it show up in a future version of Safari would be awesome.
I found two Mozilla bugs filed regarding lazy loading support, 1542784 and 947427. Unfortunately there hasn’t been any movement on either one.