See post at Schneier's blog on "MySpace Used as Forensics Tool".It's a lesson to web surfers. Before you fill up those personal into the forms by BBS/BLOG/IRC/Mailinglist and other Myspace-like cyber sites, you'd better prepare to let those info known by everybody in the planet. Or don't do that.
At other side, that reflects the value of the technology of web data mining, not just web search engines like Google, Yahoo, and Baidu, and not just so-called community search engines like Google Blog Search and Qihoo, etc. The next generation web info mining tools should cover more applications where valued data hide themselves. The mining technology, just as today's search engine, is a kind of dual-edge sword. You can use it to protect yourself, others can make use of it to hurt you.