Pluck first introduced the community tagging and blog search engine called Shadows as a Beta in mid-July. It offers a simple way for bloggers to tag their posts rather then actually adding tag code to your posts. It also offers other collaborative capabilities which include joining web groups and discussions. Additionally, Shadows offers a blog tag search feature which can be sorted by users, groups, and listings you specifically tagged.
I first blogged about Shadows back in July in the Somewhat Frank post IceRocket and Pluck Shadows Tagging as it was offered as a Beta. Today Pluck announced Shadows 1.0 is no longer in the Beta phase in the latest Pluck Press Release. Check out Shadows and give it a try. It has a lot to offer to bloggers and non-bloggers alike.