I had to upgrade a build server running BeleniX 0.8 recently to OpenIndiana. This was needed to move to a more updated environment for building the next BeleniX release. Obviously BeleniX 0.8 being a custom-built distro based on SVR4 packaging had no upgrade path to an OpenIndiana release based on IPS.
What I actually needed was to have OpenIndiana installed into a new ZFS boot environment and boot from it which would allow me to go back to BeleniX 0.8 if I needed it. I of course had the same capability in BeleniX via the Network Installer that I had written earlier. Now I needed the same for OpenIndiana. So I spent a week modifying and experimenting and I now have a network installer for OpenIndiana. You can grab it from http://www.belenix.org/binfiles/install_openindiana.
Obviously I will have to update the BeleniX version once the next release is out since we will be moving to an RPM5 based packaging. This network install technique can be adapted to any distro and will allow a multi-boot setup based on ZFS boot environments. Apart from this there are other possibilities that I can think of. At present the network install script uses the package collection from the slim_install package group. A new package group for a non-GUI base environment can be leveraged via this script. This can also play a part in a minimal CD based environment to quickly install predefined setup, something not unlike the Automated Installer but without all that complexity. If gPXE can be properly made to handle booting an OpenSolaris kernel then it will be possible to deliver such install environments over HTTP for eg.