I have a CentOS6 server here so I just installed kile-2.1-1.el6.x86_64 from the epel repo (plus a shedload of dependencies :-) This machine has a full installation of TeX, and the kpsewhich command reports the package is at:
/usr/share/texmf/tex/latex/beamer/themes/color/beamercolorthemebeaver.sty
This test file compiles correctly from the command line and from within Kile:
\documentclass{beamer}
\usepackage{fix-cm}
\usecolortheme{beaver}
\begin{document}
\begin{frame}
Test
\end{frame}
\end{document}
What have you got that is different (apart from an older version of Kile)? It may be something to do with the switch from the KDE3 to KDE4 libraries (and I don't know how to fix that).
///Peter