It is great to see innovation in the compiler space.
I happened to use LLVM for a compiler project and it is amazing to see how flexible the framework is.
LLVM was created by Chris Lattner at UIUC in the course of his PhD research.
It really undermines the need to be a very good programmer to create a project on that scale. Apple employed Chris to adopt LLVM to MAC OS X as they were stuck with GCC version 4.2 as the later version of GCC moved to GPL v3.
The Clang frontend recently has advanced enough to be able to build a linux kernel. Also XCode includes LLVM-clang.
Apparently clang is much faster at building code and also gives more meaningful error messages. Though the performance difference in terms of actual binary is not huge, the scope for improvement is very high as it is easier to implement optimizations than in GCC.
The BSD projects have been looking for quite some time to adopt a compiler with a more appropriate license, since the license of GCC is restrictive when compared to BSD license. There were quite some BSD licensed compiler projects in between, most notable PCC. But I am betting on LLVM to take the place of GCC in the BSD world pretty soon.
It is always good to have competing projects just to keep the people involved on their toes and foster innovation.