Facebook is now making (very) limited public search listings available to people who are not logged in to Facebook on an opt out basis.
Additionally, they will soon be allowing search engines to crawl these Public Search listings. Presumably the business rationale it to increase traffic from search engines.
Myspace has allowed search engines to crawl profile pages for some time.
Oddly enough though, according to Comscore, in July 5% of Facebook’s visits came from Google but only 4% of MySpace’s visits came from Google. It may be that there won’t be much of a lift in traffic from this move after all.