The konqueror line is obsolete since konqueror 2.0 is from kde 2.0. I just
tested 4.3.2 and it uses pipelining.
Firefox OTOH doesn't (just tested it). The bad thing about Firefox is that
it opens multiple connections but keeps each connection alive after the data
are transmitted (!). What a misuse of resources!
However, the support is there and all HTTP/1.1 servers support it. AFAIK,
only akamai servers don't support keepalives (they support HTTP/1.0 only).