It's the application you use to manage NetInfo...Geesh!
Remember that, under the hood, OS X & Rhapsody/OS X Server are basically NextStep-derived. If you don't remember NeXT, it was the company that Steve Jobs started after he left Apple.
NetInfo was (and presumably is) a way to maintain configuration and authentication data on a single master server for a bunch of networked clients (Ala Sun's NIS, or Microsoft's Active directory/NT Domain services), and dates from back in the day, as the vernacular goes.
Personally, I've always thought it was a tool of the devil and should be destroyed... It is (or at least was) intertwined with the fabric of the OS the way various types of parasitic alien tissue would intertwine around Spock's spinal column in the old Star Trek episodes*. I can only hope that it's replaced with something a little more robust, presumably something LDAP-based, or the like, and decoupled a little from the guts of the OS, making it easier to TURN IT OFF.
*For a graphic portrayal of my personal NetInfo-induced pain, please reference any old Star Trek episode where Spock grimaces and passes out, causing Dr. McCoy to exclaim 'It's woven it's way into the tissue of his spine, Jim!'. Spock will then proceed to spend the rest of the episode doing nothing but lay in sickbay, making the blinkilights go faster.
NetInfo seems to be more-less okay on MacOS X pb.
The important thing is that there is no point in modifying /etc/services anymore when you're installing UN*X stuff like samba. Instead, you have to add the info inside the NetInfo tree (in the services directory).
A much-needed added step to porting to the POSIX layer with no palapable return other then a proprietary black hole for your configuration data. When this was new, we all thought X.500 was going to be the open-spec game to be playing. Well, now it is, so I hope that they dump it.