I really don't understand this point of view. LLVM is really cool, but its not revolutionary. It, like most (all?) other modern compilers uses an IR. GCC - the obvious comparison - has gone through at least two over the years. The original 1987 release had one. Promoting IR as an interop layer isn't new either (1992: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.41.1...). The JVM+CLR were both around by the time LLVM came to be too; CLR was supposed to be multi-language from the start. Modern GCC's IR layers were around not much later.

At the time apple bet on LLVM, it wasn't nearly as polished as it is now: they didn't pick it because it was great, but because of the liberal licensing (just like khtml, for that matter).

That's not to denigrate LLVM - clean, modern code that's easy to use is wonderful - but that doesn't make it a wonder. If I had to guess, I bet it's like 99% of other projects: lots of work, copying good ideas liberally from several sources, and solving the right problem at the right time.