I have now been approved and am a member of Blogpower (check out the links on the right). I like the group and only certain practical considerations have prevented me joining sooner. There are two things I think it does better than any other online community I've seen:
1) It creates a space for a reasoned dialogue between people who disagree. Too many bloggers are terribly concerned for rules and netiquette but miss the more important need to be respectful and friendly; to build a sense of community that makes everyone confident to venture their opinions and good-natured when they disagree.
2) It exemplifies the incredible connections that can form on the Internet. The sheer diversity of Blogpower, the range of backgrounds and experiences brought together, is amazing. You never know where you're going to find your audience and normally our social circle is so restricted. The Internet can offer us a way out of those narrow bounds and I see so many examples of Blogpower doing so. Wonderful.