`\documentclass[9pt]{beamer}
\begin{document}
\begin{frame}
\begin{align}
\begin{array}{c}
T_1T_2\leq0 %questo non e' allineato verticalmente
\end{array}&
\Rightarrow
\left\{ \begin{array}{l} %questo ora e' incolonnato
\tau_1=\frac{T_1-T_2}{2}\\
\tau_2=\frac{T_2-T_1}{2}\\
\tau_3=\frac{T_1+T_2}{2}
\end{array} \right. \label{eq:sol1}\\
\begin{array}{c}
T_1T_2>0\text{ and } |T_1|\leq|T_2|
\end{array}&
\Rightarrow
\left\{ \begin{array}{l}
\tau_1={T_1-\frac{T_2}{2}}\\
\tau_2=\frac{T_2}{2} \\
\tau_3=\frac{T_2}{2}
\end{array} \right.\label{eq:sol2}\\
\begin{array}{c}
T_1T_2>0 \text{ and }|T_1|>|T_2|
\end{array}&
\Rightarrow
\left\{ \begin{array}{l}
\tau_1=\frac{T_1}{2}\\
\tau_2=T_2-\frac{T_1}{2} \\
\tau_3=\frac{T_1}{2}
\end{array} \right.\label{eq:sol3}
\end{align}
\end{frame}
\end{document}
`
Questo mi sembra inclonnato bene e gli and sono sistemati in modo testo