why? in clojure strings can be multiline already. so there is no point in triple quotes.
1. Long regular expression strings that have quote marks involved. I'm not a fan of large, complex regexes, but a lot of people dislike the line-noise added by escaping.
2. Docstrings that may have quotes in them.
It's to remove the string escaping that makes literals look different from the strings they describe.
Thinking about it, I guess triple-quoted strings also facilitate doctests involving strings that would otherwise be really awkward to read/write.