jquery UI 1.8rc1 build routine misses effects
Line 89 of build.xml in jQuery UI 1.8rc1 misspells the file names for effects so they are missed form the full build.
<fileset dir="${src.dir}/" includes="jquery.ui.*.js, effects.*.js" excludes="${core.files}" />
should be
<fileset dir="${src.dir}/" includes="jquery.ui.*.js, jquery.effects.*.js" excludes="${core.files}" />