I love Apple’s efforts to implement web standards and document them well, but I really don’t understand the use for grid lanes. Is there anything I can use it for besides Pinterest clones?
Masonry layouts are a general class of layouts. They aren't specific to Pinterest.
yeah, but realistically in what other places would you use them?
Whenever your designer team decides to use that layout. It seems to lend well for social medias (I have been requested to apply it in a non-art social media) and galleries.