Hm, it's strange.
1. # cat /opt/etc/ipkg.conf
the output should contain some commented out lines (starting with '#' - in case you don't know) and these two lines:
dest root /
src/gz optware http://ipkg.nslu2-linux.org/feeds/optware/mbwe-bluering/cross/unstable
2. # cat /etc/ld.so.conf
it should print
and maybe something more
3. If everything's fine so far, run # ldconfig
That's it, I guess. Also, in case you don't want to constantly bother yourself with ldconfig, check out ldso-runpath-enabled firmware. It's "backwards" compatible with the original FW (as far as I know) and elevates the annoying necessity of editing /etc/ld.so.conf and "ldconfig'ing", not to mention that some optware stuff just wont' work unless you solve the ldso-runpath issues due to conflicting stock and optware libs (like ncurses).