IceRocket and Pluck are both making huge strides into the blog search and tagging arena by offering tagging methods for your blog posts. Check out this link on IceRocket for instructions on how you can begin tagging. Thanks to Steve Rubel with additional support from IceRocket CEO, Blake Rhodes, for bringing IceRocket tagging to light.
Additionally, Pluck has released the Pluck Shadows Beta. It is a new blog search by Pluck which allows you to tag pages that are already published via the Shadows web site or a browser toolbar you can install to tag pages. It took me a second to figure out how this all works since it is not using the conventional tagging method of actually placing tags into the code of your posts. However, this unique tagging method is easy to use and should have appeal to both the technical and non-technical blogger. TechCrunch does a wonderful profile on Shadows here.