As the private equity market heats up, the firms once shrouded in secrecy are beginning to make themselves heard.

Last year was a landmark one for private equity (PE) firms. They gained billions in capital from eager investors. They joined forces on huge buyouts of companies that would once have not been considered in play, like the $33 billion deal for Hospital Corporation of America. And they raised speculation - grounded or not - that the $100 billion buyout is not ...