Mercurial provides the same "killer feature", which I think nullifies any "killer feature" status for git (implies exclusivity, I believe).
I can't believe I fell for a celebrity endorsement. ;)
Really, I'd be fine with any fast distributed VCS, which means nearly all of them these days. (sorry Darcs). The ease of setup ("If you have SSH you have a git server") feature is also very nice, but I don't think it's exclusive to git.