Self-directed IRAs have been around since 1975, shortly after Congress passed the ERISA legislation in 1974. Many unions and insurance companies have been doing it for longer than that. In the past, most banks and administrators would only do it for their best or wealthiest clients.
There have been many books and articles in the Wall Street Journal, Forbes, and other publications discussing the capability of self-directed IRAs. Google currently has information on the subject, which has been growing steadily for years.
Of course, IRS forms and publications (590 and 560 in particular) discuss these types of accounts as well, but how many people want to read those forms?