\documentclass{article}
\usepackage{pst-node}\SpecialCoor
\makeatletter
\def\psGetEdgeA#1#2{tx@NodeDict begin 0.0 0.0 neg 0.0 0.0 0 0
/N@#1 /N@#2 InitNC { NCCoor } if pop pop \tx@UserCoor end}
\def\psGetEdgeB#1#2{tx@NodeDict begin 0.0 0.0 neg 0.0 0.0 0 0
/N@#1 /N@#2 InitNC { NCCoor } if 4 2 roll pop pop \tx@UserCoor end}
\makeatother
\begin{document}
\Huge
\hspace*{4cm}\rnode{B}{Node B}
\vspace{2cm}
\rnode{A}{Node A}
\ncline{A}{B}
\pscircle*[linecolor=blue,opacity=0.4](!\psGetEdgeA{A}{B}){10pt}
\pscircle*[linecolor=blue,opacity=0.4](!\psGetEdgeB{A}{B}){10pt}
\end{document}