media-tv/xbmc-9999 Weather plugin (and maybe add ons generally) needs dev-python/simplejson to work.
only weather.wunderground requires it. we don't include dependencies for addons that aren't part of xbmc proper. so if XXX addon d/l-ed from the internet needs YYY pkg, that's the end user's problem, not the xbmc ebuild's.
should be all set now in the tree; thanks for the report! Commit message: Require simplejson for the weather plugin http://sources.gentoo.org/media-tv/xbmc/xbmc-9999.ebuild?r1=1.93&r2=1.94