Last week, while we were all recovering from turkey-induced narcolepsy, the LLVM team released version 3.0. There's a lot going on in this compiler and tool collection, so I'll let the change-log speak for itself. You can read the full release notes here. Pasted from here:

LLVM 3.0 includes several major changes and big features:

• llvm-gcc is no longer supported, and not included in the release. We recommend switching to Clang or DragonEgg.
• The linear scan register allocator has been replaced with a new "greedy" register allocator, enabling live range splitting and many other optimizations that lead to better code quality. Please see its blog post or its talk at the Developer Meeting for more information.
• LLVM IR now includes full support for atomics memory operations intended to support the C++'11 and C'1x memory models. This includes atomic load and store, compare and exchange, and read/modify/write instructions as well as a full set of memory ordering constraints. Please see the Atomics Guide for more information.
• The LLVM IR exception handling representation has been redesigned and reimplemented, making it more elegant, fixing a huge number of bugs, and enabling inlining and other optimizations. Please see its blog post and the Exception Handling documentation for more information.
• The LLVM IR Type system has been redesigned and reimplemented, making it faster and solving some long-standing problems. Please see its blog post for more information.
• The MIPS backend has made major leaps in this release, going from an experimental target to being virtually production quality and supporting a wide variety of MIPS subtargets. See the MIPS section below for more information.
• The optimizer and code generator now supports gprof and gcov-style coverage and profiling information, and includes a new llvm-cov tool (but also works with gcov). Clang exposes coverage and profiling through GCC-compatible command line options.

If you're already an LLVM user or developer with out-of-tree changes based on LLVM 2.9, this section lists some "gotchas" that you may run into upgrading from the previous release.

• LLVM 3.0 removes support for reading LLVM 2.8 and earlier files, and LLVM 3.1 will eliminate support for reading LLVM 2.9 files. Going forward, we aim for all future versions of LLVM to read bitcode files and .ll files produced by LLVM 3.0.
• Tablegen has been split into a library, allowing the clang tblgen pieces to now live in the clang tree. The llvm version has been renamed to llvm-tblgen instead of tblgen.
• The LLVMC meta compiler driver was removed.
• The unused PostOrder Dominator Frontiers and LowerSetJmp passes were removed.
• The old TailDup pass was not used in the standard pipeline and was unable to update ssa form, so it has been removed.
• The syntax of volatile loads and stores in IR has been changed to "load volatile"/"store volatile". The old syntax ("volatile load"/"volatile store") is still accepted, but is now considered deprecated and will be removed in 3.1.
• llvm-gcc's frontend tests have been removed from llvm/test/Frontend*, sunk into the clang and dragonegg testsuites.
• The old atomic intrinsics (llvm.memory.barrier and llvm.atomic.*) are now gone. Please use the new atomic instructions, described in the atomics guide.
• LLVM's configure script doesn't depend on llvm-gcc anymore, eliminating a strange circular dependence between projects.