I am trying to suppress the blank space on the top of the itemize environment. I tried to use the trick described here, yet it does not seem to work when working with \multicolumn
\documentclass{article}
\usepackage{longtable}
\usepackage{booktabs}
\usepackage{enumitem}
\usepackage{array} % Thanks daleif !
\makeatletter
\newcolumntype{P}[1]{>{\@minipagetrue}p{#1}}
\makeatother
\setlist[itemize]{noitemsep, topsep=0pt, leftmargin=*}
\begin{document}
\begin{longtable}{p{4cm}p{4cm}p{4cm}}
\toprule
\textbf{col1} & \textbf{col2} & \textbf{col3} \\
\midrule
foo & bar & zbb \\
foo & \multicolumn{2}{P{8cm}}{\begin{itemize}\item foo \item bar\end{itemize}}\\
\bottomrule
\end{longtable}
\end{document}

longtable? As for your last question, that's just a MWE, I wouldn't need amulticolumnhere :) – Jan 29 '15 at 18:54minipages in these cases. As for my last question, I knew what the answer was. :-) – karlkoeller Jan 29 '15 at 19:38