I would love to bring this back on top of awareness. I would really love to have something out of the box with Highcharts.

The ability to do this is well-documented in tikz which I have used in latex.

For example,

\begin{tikzpicture}
\node (p1) at (0,0) [circle,draw] {$P_1$};
\node (p2) at (1,0) [circle,draw] {$P_2$};
\node (p3) at (3,0) [circle,draw] {$P_3$};
\node (p4) at (5,0) [circle,draw] {$P_4$};
\node (p5) at (6,0) [circle,draw] {$P_5$};
\node (p6) at (7.5, 0) [circle,draw] {$P_6$};
\node (p7) at (9,0) [circle,draw] {$P_7$};
\node (p8) at (11,0) [circle,draw] {$P_8$};
\node (p9) at (12,0) [circle,draw] {$P_9$};
\node (p10) at (13.5,0) [circle,draw] {$P_{10}$};

\node (inizio) at (0, -3) [inner sep=1pt,label=below:$1986$] {};
\node (t2) at (1,-3) [inner sep=1pt,label=below:$1988$] {};
\node (t3) at (3,-3) [inner sep=1pt,label=below:$1992$] {};
\node (t4) at (5,-3) [inner sep=1pt,label=below:$1996$] {};
\node (t5) at (6,-3) [inner sep=1pt,label=below:$1998$] {};
\node (t6) at (7.5, -3) [inner sep=1pt,label=below:$2001$] {};
\node (t7) at (9,-3) [inner sep=1pt,label=below:$2004$] {};
\node (t8) at (11,-3) [inner sep=1pt,label=below:$2008$] {};
\node (t9) at (12,-3) [inner sep=1pt,label=below:$2009$] {};
\node (fine) at (13.5, -3) [inner sep=1pt,label=below:$2012$] {};
%
%\path (D) edge node{} (A)
% edge node{} (C)
% (E) edge node{} (A)
% edge node{} (B)
% (F) edge node{} (D);
\draw[thick,->] (p4) .. controls +(down:2mm) and +(down:20mm).. (p2);
\draw[thick,->] (p4) -- (p3);
\draw[thick,->] (p5) .. controls +(down:2mm) and +(down:30mm).. (p1);
\draw[thick,->] (p5) .. controls +(up:2mm) and +(up:25mm).. (p2);
%\draw[->] (p6) .. controls +(up:2mm) and +(up:20mm).. (p4);
\draw[thick,->] (p7) .. controls +(left:2mm) and +(down:55mm).. (p1);
\draw[thick,->] (p7) .. controls +(up:2mm) and +(up:35mm).. (p2);
\draw[thick,->] (p7) .. controls +(down:5mm) and +(down:20mm).. (p5);
\draw[thick,->] (p7) -- (p6);
\draw[thick,->] (p8) .. controls +(up:5mm) and +(up:50mm).. (p1);
\draw[thick,->] (p8) .. controls +(down:2mm) and +(down:30mm).. (p4);
\draw[thick,->] (p8) .. controls +(left:2mm) and +(up:20mm).. (p6);
\draw[thick,->] (p9) .. controls +(up:5mm) and +(up:40mm).. (p3);
\draw[thick,->] (p10) .. controls +(down:2mm) and +(down:40mm).. (p6);
\draw[thick,->] (p10) .. controls +(up:5mm) and +(up:20mm).. (p8);

\draw[->] (inizio) -- (fine);
\end{tikzpicture}

would output something like this:

https://assets.mypatentideas.com/images/fiddle/example.png

Network Architecture diagrams using highcharts would be really great.

If I understand correctly, it would be easy to extend scatter plot with this? So that one could compute x,y positions for nodes and then draw lines for links between nodes?

What I would like to see in addition is the possibility to use this diagram in a time-series fashion. When you have a time-series of such diagrams and you can move backwards and forwards.

Is there any documentation on how to write plugins? On what is internal API and so on?

Support for small world diagrams would indeed be great. The interactivity of highcharts would be excellent for managing social networks, word relationships, etc..

I also agree that this will be a great new product for highcharts..The number of well written network topology graphing libraries in javascript is very small now and lot of things in the highchart can be easily extended to this area.

I see the idea is already quite old, but I hope you would still consider it. Currently the most viable option is indeed protovis or d3 and frankly it is not as polished as the graphs highcharts produces.

Network layouts would be great. Now I am using vis.stanford.edu/protovis/ but it does not work on IE.