Your blog, as it's indexed by the search engines, is like a dandelion. Once you blow on it (and get it indexed by one search engine), it's going to spread all over the yard (the Internet). Picking up the pieces, as in removing your blog from the search engines, is almost an impossible task.
Google provides us with the ability to remove our blogs (web sites) from the Google Search Engine - but the Google Search Engine is not the only search engine with which we should concern ourselves. With the Google Search Engine feeding, and being fed by, other search engines, what's indexed by Google today may be indexed elsewhere tomorrow, and vice versa.
To get an idea how the major search engines feed, and are fed by, each other, take a look at either the Search Engine Partnership Chart, or at the Search Engine Decoder. Both diagrams are animated illustrations, and both use Flash and / or other scripts. If you have Firefox, or another browser that block scripts, you'll have to permit "ihelpyou.com" or "search-this.com", respectively, if you are to get the full picture from the animations.
But check out what's provided - you may be surprised at the complexity - I was.