Yes, the MikTeX Package Manager does still exist for Linux, they are just in the process of porting major parts of MikTeX and don't ship the miktex-tools package any more.
Download the sources from the MikTeX page. Untar and just follow the directions in the README.unx file. For some obscure reason, lynx must be installed, also (less obscure) curl-devel.
# cmake -G "Unix Makefiles" -DMIKTEX_INSTALLROOT=/usr/share/texmf (or whereever your texmf tree is)
# make install
Add the installation path to the root PATH (just for convenience):
# export PATH=$PATH:/usr/local/bin
Or link mpm in /sbin:
# cd /sbin
# ln -s /usr/local/bin/mpm
For mpm usage, check man mpm or Christian Schenk's blog entry. Don't forget to run
after making changes to get texlive to find the changed packages.
NB: mpm doesn't compile with gcc 4.3.1 (e.g. openSuSE 11) but can be patched successfully.