Like this?
\documentclass[a4paper]{article}
\usepackage{tikz}
\usetikzlibrary{decorations.pathreplacing,}
\newcommand{\tikzmark}[1]{\tikz[baseline={(#1.base)},overlay,remember picture] \node[outer sep=0pt, inner sep=0pt] (#1) {\phantom{A}};}
\begin{document}
\begin{itemize}
\item Example I
\item Example II
\begin{itemize}
\item SubExample II-1\tikzmark{a}
\item SubExample II-2\tikzmark{b}
\end{itemize}
\item Example III
\item Example IV
\end{itemize}
\begin{tikzpicture}[overlay, remember picture,decoration={brace,amplitude=2pt}]
\draw[decorate,thick] (a.north east) -- (b.south east) node[midway, right=0.1cm] {$=$}node[midway, right=0.5cm,text=black,text width = 2in,] {Text comes here to describe these to items and justify for your case};
\end{tikzpicture}%
\end{document}

With a macro
You can make a macro, if you end up using it for many times.
\documentclass[a4paper]{article}
\usepackage{tikz,xparse}
\usetikzlibrary{decorations.pathreplacing,}
\newcommand{\tikzmark}[1]{\tikz[baseline={(#1.base)},overlay,remember picture] \node[outer sep=0pt, inner sep=0pt] (#1) {\phantom{A}};}
%% syntax
%%%\mybrace{<first>}{<second>}[<Optional text>]
\NewDocumentCommand\mybrace{mmo}{%
\IfValueTF {#3}{%
\begin{tikzpicture}[overlay, remember picture,decoration={brace,amplitude=1ex}]
\draw[decorate,thick] (#1.north east) -- (#2.south east) node[midway, right=0.1cm] {$=$}node[midway, right=0.5cm,text=black,text width = 2in,] {{#3}};
\end{tikzpicture}%
}%
{%
\begin{tikzpicture}[overlay, remember picture,decoration={brace,amplitude=1ex}]
\draw[decorate,thick] (#1.north east) -- (#2.south east);
\end{tikzpicture}%
}%
}%
\begin{document}
\begin{itemize}
\item Example I
\item Example II
\begin{itemize}
\item SubExample II-1\tikzmark{a}
\item SubExample II-2\tikzmark{b}
\end{itemize}
\item Example III
\item Example IV
\end{itemize}
\mybrace{a}{b}[Text comes here to describe these to items and justify for your case]
\end{document}

Response to the edited query
Here we make some assumptions:
- The sub items can have variable length
- But they are short enough not to span multiple lines (for if they do, then description becomes meaningless)
With these assumptions, you can put the sub itemize environment inside a minipage of width equal to 0.5\textwidth. You can vary this width as per your need.
\begin{itemize}
\item Example I
\item Example II
\begin{minipage}[t]{0.5\textwidth}
\begin{itemize}
\item SubExample II-1 just more length\tikzmark{a}
\item SubExample II-2\hfill\tikzmark{b}
\end{itemize}
\end{minipage}
\item Example III
\item Example IV
\end{itemize}
\mybrace{a}{b}[Text comes here to describe these to items and justify for your case]
Another option will be to put each sub item inside a \parbox of width 0.5\textwidth:
\documentclass[a4paper]{article}
\usepackage{tikz,xparse}
\usetikzlibrary{decorations.pathreplacing,}
\newcommand{\tikzmark}[1]{\tikz[baseline={(#1.base)},overlay,remember picture] \node[outer sep=0pt, inner sep=0pt] (#1) {\phantom{A}};}
%% syntax
%%%\mybrace{<first>}{<second>}[<Optional text>]
\NewDocumentCommand\mybrace{mmo}{%
\IfValueTF {#3}{%
\begin{tikzpicture}[overlay, remember picture,decoration={brace,amplitude=1ex}]
\draw[decorate,thick] (#1.north east) -- (#2.south east) node[midway, right=0.1cm] {$=$}node[midway, right=0.5cm,text=black,text width = 2in,] {{#3}};
\end{tikzpicture}%
}%
{%
\begin{tikzpicture}[overlay, remember picture,decoration={brace,amplitude=1ex}]
\draw[decorate,thick] (#1.north east) -- (#2.south east);
\end{tikzpicture}%
}%
}%
\begin{document}
\begin{itemize}
\item Example I
\item Example II \par
%\begin{minipage}{0.5\textwidth}
\begin{itemize}
\item \parbox[t]{0.5\textwidth}{SubExample II-1 just more length as they come here}\tikzmark{a}
\item \parbox{0.5\textwidth}{SubExample II-2}\tikzmark{b}
\end{itemize}
% \end{minipage}
\item Example III
\item Example IV
\end{itemize}
\mybrace{a}{b}[Text comes here to describe these to items and justify for your case]
\end{document}

xparsepackage installed. – Feb 20 '14 at 09:03