Two things popped up on my radar recently:

gvn, Google's wrappers around Subversion to help them work in their code-review heavy workflow. Even if you're not into code reviews, tkdiff integration is a nice improvement over colordiff or FileMerge.

gold, a new ELF linker built with giant binaries in mind. When you're building 900MB+ static binaries routinely, linking speed matters. gold claims to be at least 5x faster currently. Even if you have a massive distcc cluster, linking is still serial. One of gold's future design goals is to be concurrent and that would be pretty awesome. Imagine how fast I could link with a concurrent linker on my 8-core Mac Pro! Not that using an ELF linker under Leopard helps much since OS X uses Mach-O binaries but hey, there's always cross-compiling.

BTW, Ian Lance Taylor, the author of gold, has an excellent series of blog articles on linkers.