I have POCO 1.4.5 compiled/installed and could not get Ogre 1.8.1 to build with POCO selected as a thread provider with threading config value of 2. I'm including the makefile error below as it looks like it revolves around OgreWorkQueue.h.
In file included from /home/xtitus/ogre_src_v1-8-1/OgreMain/include/OgreRoot.h:39:0,
/home/xtitus/ogre_src_v1-8-1/OgreMain/include/OgreWorkQueue.h: At global scope:
/home/xtitus/ogre_src_v1-8-1/OgreMain/include/OgreWorkQueue.h:475:4: error: expected ‘;’ at end of member declaration
/home/xtitus/ogre_src_v1-8-1/OgreMain/include/OgreWorkQueue.h:532:3: error: expected ‘;’ at end of member declaration
make: *** [OgreMain/CMakeFiles/OgreMain.dir/src/OgreBillboardChain.cpp.o] Error 1
make: *** [OgreMain/CMakeFiles/OgreMain.dir/all] Error 2
Ubuntu 12.04 x64 with GNU compiler