The package name (nodejs-git 20110613-1) confused me. I assumed it was a snapshot from 2011-06-13, but after looking at the PKGBUILD file I see that it is cloning the github repo. My mistake.
fwiw, aur packages with the -(cvs|hg|git|svn) suffix usually track the development, while the date actually refers to when the build was last updated. Installing the package will actually give you today's date as the version tag. I can see why the confusion happens, though :)
Hm, as a general rule, I'd actually suggest continuing to avoid such packages in general, unless you know that they're what you need: you need to track whether there's been a source code update, whether someone broke the upstream build, whether your current versions of other packages depend on it
(example: x264-git, pretty much requires that you also install libav-git/mplayer-git, and then of course blender doesn't work, and so on. It can become quite messy at times.)