Yes, a major appeal of pipelining to me is efficiency with respect to open connections. It's easier to monitor the progress of one connection sending multiple HTTP verbs than multiple connections each sending one verb.

Whether multiple verbs over one connection are processed by the given httpd more efficiently than single verbs over single connections is another issue. IME, a purely client-side perspective, pipelining does speed things up. But then I'm not using Firefox to do the pipelining.

I'm sure the team reponsible for Googlebot would have some insight on this question. (And I wonder how much SPDY makes the bot's job easier?)

In any event, multiplexing would appear to solve the open connections issue. And I don't doubt it will consistently beat HTTP/1.1 pipelining alone. I'm a big fan of multiplexing (for peer-to-peer "connections"), but I am perplexed by why it's being applied at the high level of HTTP (and hence restricted to TCP, and all of its own inefficiencies and limitations).

I'm curious about something you said earlier. You said something about the "overhead" of using netcat. It's relatively a very small, simple program with modest resource requirements. What did you mean by overhead?