Grep with non-ascii

Hello.

I just noticed this today:

elg!ene[~]> printf "bø\nhei\nøl\n" | grep ø
grep: trailing backslash (\)
elg!ene[~]> echo $LC_CTYPE $LANG
nb_NO.ISO8859-1 nb_NO.ISO8859-1

While I have the result I envisioned with gnugrep:

elg!ene[~]> printf "bø\nhei\nøl\n" | ggrep ø
bø
øl

Also, on OpenIndiana, linux and Netbsd, grep gives the proper result.

Is lib/libc/regex the right place to look into this if I
find the time, or does anybody know this enough to know the
problem?

Regards
-- 
Eivind Nicolay Evensen