The alignment_of template is no longer necessary, now that the core language will provide alignof. Scott Meyers raised this issue at comp.std.c++, C++0x: alignof vs. alignment_of, May 21, 2009. In a reply, Daniel Krügler pointed out that alignof was added to the working paper after alignment_of. So it appears that alignment_of is only part of the current Working Draft (N2857) because it is in TR1.

Having both alignof and alignment_of would cause unwanted confusion. In general, I think TR1 functionality should not be brought into C++0x if it is entirely redundant with other C++0x language or library features.