[{Category [page=".."] 
    format="_list_|gallery" 
    sort="_alphabetic_|none" 
    headlines="_alphabetic_lnone|"
    attachments="yes|_no_"
    gallery-width=n (default: 4)
    thumbnails="yes|_no_"
    thumbnailWidth=n 
    thumbnailHeight=n
    pagesize=n (maximum number of entries to be displayed
                per page, default: no limit)
}]

The CategoryPlugin is part of the CategoryAndArchiveExtensions. See there for a detailed explanation.

-- Jens Gulden