It's sensitive, anywhere that the light can bounce. Mine is behind my computer, behind my TV, never misses a press.
http://flirc.tv/downloads
You can pair it on everything:
windows, linux, mac.
I've fixed all the issues so it should work on all versions of windows and the mac (excluding PPC). Any distro on linux is supported, and the rasperry pi supports the commandline interface and xbmc plugin.