The copy of the man pages I have for cat (GNU coreutils 184.108.40.206-f088d-dirt January 2008) says this:
"-v, --show-nonprinting "
use ^ and M- notation, except for LFD and TAB;"
it doesn't strip control characters, but maps them to a different form. The FreeBSD entry for cat has a similar, but not identical description for the -v option.
Information about American English usage here and here. Floating point issues? Please read this before posting. — emc