] BlogThis! - "Blog" stands for web log, your own online
] journal for publishing information on the web. To use
] this feature you must set up a free account with Google's
] Blogger service. If you have an existing Blogger account
] already, you can use that as well. When you use
] BlogThis!, you create a blog post that points to the web
] page you're visiting. If you highlight text on the web
] page, that text will also appear in your blog post.

In the new beta version of the Google toolbar, there's a "blog this" button that looks like it'll work very similarly to how Memestreams works...

Google Toolbar Blogger