vim74-kaoriya-win32\plugins\にプラグインをディレクトリごと入れるだけで、認識されます。
昔気づかなくてvim74-kaoriya-win32\vim74\に展開して入れてました・・。
plugins
plugins/autofmt
plugins/autofmt/autoload
plugins/autofmt/autoload/autofmt
plugins/autofmt/doc
plugins/autofmt/test
plugins/autofmt/tools
plugins/golang
plugins/golang/autoload
plugins/golang/autoload/go
plugins/golang/ftdetect
plugins/golang/ftplugin
plugins/golang/ftplugin/go
plugins/golang/indent
plugins/golang/plugin
plugins/golang/syntax
plugins/kaoriya
plugins/kaoriya/autoload
plugins/kaoriya/autoload/kaoriya
plugins/kaoriya/keymap
plugins/kaoriya/plugin
plugins/kaoriya/syntax
plugins/unite.vim-master
plugins/unite.vim-master/autoload
plugins/unite.vim-master/autoload/unite
plugins/unite.vim-master/autoload/unite/filters
plugins/unite.vim-master/autoload/unite/kinds
plugins/unite.vim-master/autoload/unite/sources
plugins/unite.vim-master/autoload/vital
plugins/unite.vim-master/autoload/vital/_b268d8d
plugins/unite.vim-master/autoload/vital/_b268d8d/Data
plugins/unite.vim-master/autoload/vital/_b268d8d/System
plugins/unite.vim-master/doc
plugins/unite.vim-master/plugin
plugins/unite.vim-master/plugin/unite
plugins/unite.vim-master/syntax
plugins/unite.vim-master/vest
plugins/vimdoc-ja
plugins/vimdoc-ja/doc
plugins/vimdoc-ja/syntax
plugins/vimfiler.vim-master
plugins/vimfiler.vim-master/autoload
plugins/vimfiler.vim-master/autoload/unite
plugins/vimfiler.vim-master/autoload/unite/filters
plugins/vimfiler.vim-master/autoload/unite/sources
plugins/vimfiler.vim-master/autoload/vimfiler
plugins/vimfiler.vim-master/autoload/vimfiler/columns
plugins/vimfiler.vim-master/autoload/vital
plugins/vimfiler.vim-master/autoload/vital/_13055f8
plugins/vimfiler.vim-master/autoload/vital/_13055f8/Data
plugins/vimfiler.vim-master/autoload/vital/_13055f8/System
plugins/vimfiler.vim-master/autoload/vital/_13055f8/Vim
plugins/vimfiler.vim-master/doc
plugins/vimfiler.vim-master/plugin
plugins/vimfiler.vim-master/syntax
plugins/vimfiler.vim-master/vest
plugins/vimproc
plugins/vimproc/autoload
plugins/vimproc/autoload/vimproc
plugins/vimproc/doc
plugins/vimproc/plugin