rm is not part of MinGW. The rm executable shipped with RC2 comes from the wxWidgets "extra" package: ftp://biolpc22.york.ac.uk/pub/ports/mingw32/extra.zip
The extra packages comes from unxutils unxutils.sourceforge.net
That is not quite true, and even dangerous.
The files shipped with RC2 are from the wxWidgets package. Fullstop.
It is true that the files contained in this wxWidgets "extra" package were taken from the unxutils package by J. Smart back in 2000. However, the current unxutils files are different from the "extras" files, and they are different from the files found in the MinGW distribution, too.
Most importantly, the unxutils package contains
make 3.78!
This means that if you install this archive overwriting the existing files on your hard disk,
you will break your MinGW installation! Many source distributions (including wxWidgets) require
make 3.8 to compile. If you replace it with
make 3.78, you will get strange, unexplainable errors.
The "extras" archive only contains a very limited choice of "basic tools", no build tools. Thus, the "extras" archive is safe to unzip, while the other one is not.