Absolutely -- I believe it was Rob's undergrad project at Brown that he brought to BBN.

The first use, if I saw, was the 'portable IP/TCP' stack  BBN did for HP/3000 and a couple of other systems.  That code seems to have been lost.  I have asked about it on the Internet history mailing list.  I had a copy of it one time, but sadly I don't think I still do.  IIRC The original PDP-11 IP implementation which ran on a couple of dedicated systems, whose names/function I frankly do not remember) was also based on a version of this code.  I think it ran something like RT-11 or DOS-11 and then started the IP code -- basically RTR style today.   Later it morphed into Rob's Vax BSD  4.1 specific stack,  which we ran at UCB on a couple of the systems using 3M Xerox board.  This latest until 4.1A and Joy's rewrite and I want to say we switched in Interlan 10M boards then.  We have a couple of the 3Com boards, but because of the lack of buffering, they were a bear to use and stopped as soon as we got the Interlan one. 

Anyway, all of these IP/TCP stacks used Rob's mbuf code.  Which was a blessing and a curse.  By writing his own, he avoids huge changes/integration into the memory system, but it also helped to make BSD such a mess under the covers because there were so many private memory managers between the network, the I/O systems etc...  As discussed previously on the TUHS list, the one thing Risner really did well had a uniform memory design.   Later BSD's moved to Mach and tried to clean this up a little, but the network code was by then so screwed into Rob's mbuf scheme, it stayed around a long time.  Werner -- what is the state of this these days in FreeBSD is it still there?